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227 lines
6.5 KiB
Diff
227 lines
6.5 KiB
Diff
From 8851ac5dfa652434a8e031883314a8fd0226fecf Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Mon, 4 Apr 2016 16:03:18 +0100
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Subject: [PATCH] bcm2835-sdhost: Firmware manages the clock divisor
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The bcm2835-sdhost driver hands control of the CDIV clock divisor
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register to matching firmware, allowing it to adjust to a changing
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core clock. This removes the need to use the performance governor or
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to enable io_is_busy on the on-demand governor in order to get the
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best SD performance.
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N.B. As SD clocks must be an integer divisor of the core clock, it is
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possible that the SD clock for "turbo" mode can be different (even
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lower) than "normal" mode.
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Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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---
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drivers/mmc/host/bcm2835-sdhost.c | 120 ++++++++++++++++++-----------
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include/soc/bcm2835/raspberrypi-firmware.h | 1 +
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2 files changed, 74 insertions(+), 47 deletions(-)
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--- a/drivers/mmc/host/bcm2835-sdhost.c
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+++ b/drivers/mmc/host/bcm2835-sdhost.c
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@@ -50,6 +50,7 @@
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#include <linux/of_dma.h>
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#include <linux/time.h>
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#include <linux/workqueue.h>
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+#include <soc/bcm2835/raspberrypi-firmware.h>
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#define DRIVER_NAME "sdhost-bcm2835"
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@@ -183,6 +184,7 @@ struct bcm2835_host {
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unsigned int use_sbc:1; /* Send CMD23 */
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unsigned int debug:1; /* Enable debug output */
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+ unsigned int firmware_sets_cdiv:1; /* Let the firmware manage the clock */
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/*DMA part*/
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struct dma_chan *dma_chan_rxtx; /* DMA channel for reads and writes */
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@@ -430,7 +432,7 @@ static void bcm2835_sdhost_reset_interna
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host->clock = 0;
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host->sectors = 0;
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bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
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- bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
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+ bcm2835_sdhost_write(host, SDCDIV_MAX_CDIV, SDCDIV);
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mmiowb();
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}
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@@ -1534,62 +1536,75 @@ void bcm2835_sdhost_set_clock(struct bcm
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host->mmc->actual_clock = 0;
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- if (clock < 100000) {
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- /* Can't stop the clock, but make it as slow as possible
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- * to show willing
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- */
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- host->cdiv = SDCDIV_MAX_CDIV;
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- bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
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- return;
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- }
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-
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- div = host->max_clk / clock;
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- if (div < 2)
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- div = 2;
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- if ((host->max_clk / div) > clock)
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- div++;
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- div -= 2;
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+ if (host->firmware_sets_cdiv) {
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+ u32 msg[3] = { clock, 0, 0 };
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- if (div > SDCDIV_MAX_CDIV)
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- div = SDCDIV_MAX_CDIV;
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+ rpi_firmware_property(rpi_firmware_get(NULL),
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+ RPI_FIRMWARE_SET_SDHOST_CLOCK,
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+ &msg, sizeof(msg));
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- clock = host->max_clk / (div + 2);
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- host->mmc->actual_clock = clock;
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+ clock = max(msg[1], msg[2]);
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+ } else {
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+ if (clock < 100000) {
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+ /* Can't stop the clock, but make it as slow as
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+ * possible to show willing
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+ */
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+ host->cdiv = SDCDIV_MAX_CDIV;
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+ bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
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+ return;
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+ }
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+
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+ div = host->max_clk / clock;
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+ if (div < 2)
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+ div = 2;
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+ if ((host->max_clk / div) > clock)
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+ div++;
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+ div -= 2;
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+
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+ if (div > SDCDIV_MAX_CDIV)
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+ div = SDCDIV_MAX_CDIV;
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+
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+ clock = host->max_clk / (div + 2);
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+
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+ host->cdiv = div;
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+ bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
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+
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+ if (host->debug)
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+ pr_info("%s: clock=%d -> max_clk=%d, cdiv=%x "
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+ "(actual clock %d)\n",
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+ mmc_hostname(host->mmc), input_clock,
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+ host->max_clk, host->cdiv,
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+ clock);
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+ }
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/* Calibrate some delays */
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host->ns_per_fifo_word = (1000000000/clock) *
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((host->mmc->caps & MMC_CAP_4_BIT_DATA) ? 8 : 32);
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- if (clock > input_clock) {
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- /* Save the closest value, to make it easier
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- to reduce in the event of error */
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- host->overclock_50 = (clock/MHZ);
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-
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- if (clock != host->overclock) {
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- pr_warn("%s: overclocking to %dHz\n",
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- mmc_hostname(host->mmc), clock);
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- host->overclock = clock;
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+ if (input_clock == 50 * MHZ) {
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+ if (clock > input_clock) {
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+ /* Save the closest value, to make it easier
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+ to reduce in the event of error */
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+ host->overclock_50 = (clock/MHZ);
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+
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+ if (clock != host->overclock) {
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+ pr_warn("%s: overclocking to %dHz\n",
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+ mmc_hostname(host->mmc), clock);
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+ host->overclock = clock;
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+ }
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+ } else if (host->overclock) {
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+ host->overclock = 0;
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+ if (clock == 50 * MHZ)
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+ pr_warn("%s: cancelling overclock\n",
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+ mmc_hostname(host->mmc));
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}
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}
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- else if (host->overclock)
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- {
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- host->overclock = 0;
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- if (clock == 50 * MHZ)
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- pr_warn("%s: cancelling overclock\n",
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- mmc_hostname(host->mmc));
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- }
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-
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- host->cdiv = div;
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- bcm2835_sdhost_write(host, host->cdiv, SDCDIV);
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/* Set the timeout to 500ms */
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- bcm2835_sdhost_write(host, host->mmc->actual_clock/2, SDTOUT);
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+ bcm2835_sdhost_write(host, clock/2, SDTOUT);
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- if (host->debug)
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- pr_info("%s: clock=%d -> max_clk=%d, cdiv=%x (actual clock %d)\n",
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- mmc_hostname(host->mmc), input_clock,
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- host->max_clk, host->cdiv, host->mmc->actual_clock);
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+ host->mmc->actual_clock = clock;
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}
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static void bcm2835_sdhost_request(struct mmc_host *mmc, struct mmc_request *mrq)
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@@ -1704,11 +1719,6 @@ static void bcm2835_sdhost_set_ios(struc
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log_event("IOS<", ios->clock, 0);
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- if (!ios->clock || ios->clock != host->clock) {
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- bcm2835_sdhost_set_clock(host, ios->clock);
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- host->clock = ios->clock;
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- }
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-
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/* set bus width */
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host->hcfg &= ~SDHCFG_WIDE_EXT_BUS;
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if (ios->bus_width == MMC_BUS_WIDTH_4)
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@@ -1721,6 +1731,11 @@ static void bcm2835_sdhost_set_ios(struc
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bcm2835_sdhost_write(host, host->hcfg, SDHCFG);
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+ if (!ios->clock || ios->clock != host->clock) {
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+ bcm2835_sdhost_set_clock(host, ios->clock);
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+ host->clock = ios->clock;
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+ }
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+
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mmiowb();
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spin_unlock_irqrestore(&host->lock, flags);
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@@ -1953,6 +1968,7 @@ static int bcm2835_sdhost_probe(struct p
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struct bcm2835_host *host;
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struct mmc_host *mmc;
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const __be32 *addr;
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+ u32 msg[3];
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int ret;
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pr_debug("bcm2835_sdhost_probe\n");
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@@ -2058,6 +2074,16 @@ static int bcm2835_sdhost_probe(struct p
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else
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mmc->caps |= MMC_CAP_4_BIT_DATA;
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+ msg[0] = 0;
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+ msg[1] = ~0;
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+ msg[2] = ~0;
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+
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+ rpi_firmware_property(rpi_firmware_get(NULL),
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+ RPI_FIRMWARE_SET_SDHOST_CLOCK,
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+ &msg, sizeof(msg));
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+
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+ host->firmware_sets_cdiv = (msg[1] != ~0);
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+
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ret = bcm2835_sdhost_add_host(host);
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if (ret)
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goto err;
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--- a/include/soc/bcm2835/raspberrypi-firmware.h
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+++ b/include/soc/bcm2835/raspberrypi-firmware.h
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@@ -79,6 +79,7 @@ enum rpi_firmware_property_tag {
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RPI_FIRMWARE_SET_VOLTAGE = 0x00038003,
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RPI_FIRMWARE_SET_TURBO = 0x00038009,
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RPI_FIRMWARE_SET_CUSTOMER_OTP = 0x00038021,
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+ RPI_FIRMWARE_SET_SDHOST_CLOCK = 0x00038042,
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/* Dispmanx TAGS */
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RPI_FIRMWARE_FRAMEBUFFER_ALLOCATE = 0x00040001,
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