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161 lines
5.0 KiB
Diff
161 lines
5.0 KiB
Diff
From d6b47c6dc22a1fbe2fcb5c742936a32baad60409 Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.org>
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Date: Mon, 7 Mar 2016 16:46:39 +0000
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Subject: [PATCH 167/304] bcm2835-sdhost: Only claim one DMA channel
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With both MMC controllers enabled there are few DMA channels left. The
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bcm2835-sdhost driver only uses DMA in one direction at a time, so it
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doesn't need to claim two channels.
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See: https://github.com/raspberrypi/linux/issues/1327
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Signed-off-by: Phil Elwell <phil@raspberrypi.org>
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---
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arch/arm/boot/dts/bcm2708_common.dtsi | 5 +--
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drivers/mmc/host/bcm2835-sdhost.c | 70 ++++++++++++++++++++++++-----------
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2 files changed, 50 insertions(+), 25 deletions(-)
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--- a/arch/arm/boot/dts/bcm2708_common.dtsi
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+++ b/arch/arm/boot/dts/bcm2708_common.dtsi
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@@ -136,9 +136,8 @@
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reg = <0x7e202000 0x100>;
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interrupts = <2 24>;
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clocks = <&clk_core>;
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- dmas = <&dma 13>,
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- <&dma 13>;
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- dma-names = "tx", "rx";
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+ dmas = <&dma 13>;
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+ dma-names = "rx-tx";
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brcm,overclock-50 = <0>;
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brcm,pio-limit = <1>;
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status = "disabled";
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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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@@ -185,9 +185,10 @@ struct bcm2835_host {
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unsigned int debug:1; /* Enable debug output */
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/*DMA part*/
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- struct dma_chan *dma_chan_rx; /* DMA channel for reads */
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- struct dma_chan *dma_chan_tx; /* DMA channel for writes */
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- struct dma_chan *dma_chan; /* Channel in used */
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+ struct dma_chan *dma_chan_rxtx; /* DMA channel for reads and writes */
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+ struct dma_chan *dma_chan; /* Channel in use */
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+ struct dma_slave_config dma_cfg_rx;
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+ struct dma_slave_config dma_cfg_tx;
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struct dma_async_tx_descriptor *dma_desc;
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u32 dma_dir;
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u32 drain_words;
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@@ -771,12 +772,11 @@ static void bcm2835_sdhost_prepare_dma(s
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log_event("PRD<", (u32)data, 0);
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pr_debug("bcm2835_sdhost_prepare_dma()\n");
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+ dma_chan = host->dma_chan_rxtx;
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if (data->flags & MMC_DATA_READ) {
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- dma_chan = host->dma_chan_rx;
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dir_data = DMA_FROM_DEVICE;
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dir_slave = DMA_DEV_TO_MEM;
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} else {
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- dma_chan = host->dma_chan_tx;
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dir_data = DMA_TO_DEVICE;
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dir_slave = DMA_MEM_TO_DEV;
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}
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@@ -813,6 +813,12 @@ static void bcm2835_sdhost_prepare_dma(s
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host->drain_words = len/4;
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}
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+ /* The parameters have already been validated, so this will not fail */
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+ (void)dmaengine_slave_config(dma_chan,
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+ (dir_data == DMA_FROM_DEVICE) ?
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+ &host->dma_cfg_rx :
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+ &host->dma_cfg_tx);
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+
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len = dma_map_sg(dma_chan->device->dev, data->sg, data->sg_len,
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dir_data);
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@@ -1805,28 +1811,46 @@ int bcm2835_sdhost_add_host(struct bcm28
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spin_lock_init(&host->lock);
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if (host->allow_dma) {
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- if (IS_ERR_OR_NULL(host->dma_chan_tx) ||
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- IS_ERR_OR_NULL(host->dma_chan_rx)) {
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- pr_err("%s: unable to initialise DMA channels. "
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+ if (IS_ERR_OR_NULL(host->dma_chan_rxtx)) {
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+ pr_err("%s: unable to initialise DMA channel. "
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"Falling back to PIO\n",
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mmc_hostname(mmc));
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host->use_dma = false;
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} else {
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- host->use_dma = true;
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-
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cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
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cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
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cfg.slave_id = 13; /* DREQ channel */
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+ /* Validate the slave configurations */
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+
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cfg.direction = DMA_MEM_TO_DEV;
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cfg.src_addr = 0;
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cfg.dst_addr = host->bus_addr + SDDATA;
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- ret = dmaengine_slave_config(host->dma_chan_tx, &cfg);
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- cfg.direction = DMA_DEV_TO_MEM;
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- cfg.src_addr = host->bus_addr + SDDATA;
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- cfg.dst_addr = 0;
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- ret = dmaengine_slave_config(host->dma_chan_rx, &cfg);
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+ ret = dmaengine_slave_config(host->dma_chan_rxtx, &cfg);
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+
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+ if (ret == 0) {
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+ host->dma_cfg_tx = cfg;
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+
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+ cfg.direction = DMA_DEV_TO_MEM;
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+ cfg.src_addr = host->bus_addr + SDDATA;
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+ cfg.dst_addr = 0;
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+
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+ ret = dmaengine_slave_config(host->dma_chan_rxtx, &cfg);
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+ }
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+
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+ if (ret == 0) {
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+ host->dma_cfg_rx = cfg;
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+
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+ host->use_dma = true;
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+ } else {
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+ pr_err("%s: unable to configure DMA channel. "
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+ "Falling back to PIO\n",
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+ mmc_hostname(mmc));
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+ dma_release_channel(host->dma_chan_rxtx);
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+ host->dma_chan_rxtx = NULL;
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+ host->use_dma = false;
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+ }
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}
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} else {
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host->use_dma = false;
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@@ -1948,19 +1972,21 @@ static int bcm2835_sdhost_probe(struct p
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if (host->allow_dma) {
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if (node) {
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- host->dma_chan_tx =
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- dma_request_slave_channel(dev, "tx");
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- host->dma_chan_rx =
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- dma_request_slave_channel(dev, "rx");
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+ host->dma_chan_rxtx =
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+ dma_request_slave_channel(dev, "rx-tx");
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+ if (!host->dma_chan_rxtx)
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+ host->dma_chan_rxtx =
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+ dma_request_slave_channel(dev, "tx");
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+ if (!host->dma_chan_rxtx)
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+ host->dma_chan_rxtx =
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+ dma_request_slave_channel(dev, "rx");
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} else {
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dma_cap_mask_t mask;
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dma_cap_zero(mask);
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/* we don't care about the channel, any would work */
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dma_cap_set(DMA_SLAVE, mask);
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- host->dma_chan_tx =
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- dma_request_channel(mask, NULL, NULL);
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- host->dma_chan_rx =
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+ host->dma_chan_rxtx =
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dma_request_channel(mask, NULL, NULL);
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}
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}
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