You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
44 lines
1.5 KiB
Diff
44 lines
1.5 KiB
Diff
6 years ago
|
From c03a6b0585e7c469c199d349405b3967bcf18672 Mon Sep 17 00:00:00 2001
|
||
|
|
From: Phil Elwell <phil@raspberrypi.org>
|
||
|
|
Date: Mon, 22 Jan 2018 12:17:27 +0000
|
||
|
|
Subject: [PATCH 166/454] mmc: bcm2835-sdhost: Support underclocking
|
||
|
|
|
||
|
|
Support underclocking of the SD bus in two ways:
|
||
|
|
1. using the max-frequency DT property (which currently has no DT
|
||
|
|
parameter), and
|
||
|
|
2. using the exiting sd_overclock parameter.
|
||
|
|
|
||
|
|
The two methods differ slightly - in the former the MMC subsystem is
|
||
|
|
aware of the underclocking, while in the latter it isn't - but the
|
||
|
|
end results should be the same.
|
||
|
|
|
||
|
|
See: https://github.com/raspberrypi/linux/issues/2350
|
||
|
|
|
||
|
|
Signed-off-by: Phil Elwell <phil@raspberrypi.org>
|
||
|
|
---
|
||
|
|
drivers/mmc/host/bcm2835-sdhost.c | 6 +++---
|
||
|
|
1 file changed, 3 insertions(+), 3 deletions(-)
|
||
|
|
|
||
|
|
--- a/drivers/mmc/host/bcm2835-sdhost.c
|
||
|
|
+++ b/drivers/mmc/host/bcm2835-sdhost.c
|
||
|
|
@@ -1519,8 +1519,7 @@ void bcm2835_sdhost_set_clock(struct bcm
|
||
|
|
if (host->debug)
|
||
|
|
pr_info("%s: set_clock(%d)\n", mmc_hostname(host->mmc), clock);
|
||
|
|
|
||
|
|
- if ((host->overclock_50 > 50) &&
|
||
|
|
- (clock == 50*MHZ))
|
||
|
|
+ if (host->overclock_50 && (clock == 50*MHZ))
|
||
|
|
clock = host->overclock_50 * MHZ + (MHZ - 1);
|
||
|
|
|
||
|
|
/* The SDCDIV register has 11 bits, and holds (div - 2).
|
||
|
|
@@ -1894,7 +1893,8 @@ int bcm2835_sdhost_add_host(struct bcm28
|
||
|
|
|
||
|
|
mmc = host->mmc;
|
||
|
|
|
||
|
|
- mmc->f_max = host->max_clk;
|
||
|
|
+ if (!mmc->f_max || mmc->f_max > host->max_clk)
|
||
|
|
+ mmc->f_max = host->max_clk;
|
||
|
|
mmc->f_min = host->max_clk / SDCDIV_MAX_CDIV;
|
||
|
|
|
||
|
|
mmc->max_busy_timeout = (~(unsigned int)0)/(mmc->f_max/1000);
|