From 041beb1d531f538bf62377e2ca2b4ecbaa479d75 Mon Sep 17 00:00:00 2001 From: Daniel Drake Date: Wed, 7 Sep 2011 10:22:09 +0100 Subject: [PATCH] mmc: core: add a short delay in mmc_power_off Stress-testing the runtime power management of libertas_sdio through a rmmod/insmod loop revealed that it is quite easy to cause an ETIMEDOUT failure in mmc_sdio_power_restore() leading to: libertas_sdio: probe of mmc1:0001:1 failed with error -16 Experimentation shows that a very short delay (100us) is needed in the power down path before the card can be successfully booted again. We know that this setup is lacking poweroff clamps on the card's power lines, but as only a short delay is needed, apply this unconditionally. Also bump up to 1ms sleep for extra legroom. Signed-off-by: Daniel Drake Signed-off-by: Chris Ball --- drivers/mmc/core/core.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c index 557856b6f95c..7289e999d1fc 100644 --- a/drivers/mmc/core/core.c +++ b/drivers/mmc/core/core.c @@ -1214,6 +1214,13 @@ static void mmc_power_off(struct mmc_host *host) host->ios.timing = MMC_TIMING_LEGACY; mmc_set_ios(host); + /* + * Some configurations, such as the 802.11 SDIO card in the OLPC + * XO-1.5, require a short delay after poweroff before the card + * can be successfully turned on again. + */ + mmc_delay(1); + mmc_host_clk_release(host); } -- GitLab