From 2d1bbf04a6f305528e4c1e5782134b6bbb9cc4b2 Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Thu, 5 May 2016 08:12:28 +0300 Subject: [PATCH 1/1] mmc: mmc: Fix partition switch timeout for some eMMCs commit 1c447116d017a98c90f8f71c8c5a611e0aa42178 upstream. Some eMMCs set the partition switch timeout too low. Now typically eMMCs are considered a critical component (e.g. because they store the root file system) and consequently are expected to be reliable. Thus we can neglect the use case where eMMCs can't switch reliably and we might want a lower timeout to facilitate speedy recovery. Although we could employ a quirk for the cards that are affected (if we could identify them all), as described above, there is little benefit to having a low timeout, so instead simply set a minimum timeout. The minimum is set to 300ms somewhat arbitrarily - the examples that have been seen had a timeout of 10ms but were sometimes taking 60-70ms. Signed-off-by: Adrian Hunter Signed-off-by: Ulf Hansson Signed-off-by: Ben Hutchings --- drivers/mmc/core/mmc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index c1aec06258c1..408000d9d5f8 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -235,6 +235,9 @@ static int mmc_get_ext_csd(struct mmc_card *card, u8 **new_ext_csd) return err; } +/* Minimum partition switch timeout in milliseconds */ +#define MMC_MIN_PART_SWITCH_TIME 300 + /* * Decode extended CSD. */ @@ -325,6 +328,10 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd) /* EXT_CSD value is in units of 10ms, but we store in ms */ card->ext_csd.part_time = 10 * ext_csd[EXT_CSD_PART_SWITCH_TIME]; + /* Some eMMC set the value too low so set a minimum */ + if (card->ext_csd.part_time && + card->ext_csd.part_time < MMC_MIN_PART_SWITCH_TIME) + card->ext_csd.part_time = MMC_MIN_PART_SWITCH_TIME; /* Sleep / awake timeout in 100ns units */ if (sa_shift > 0 && sa_shift <= 0x17) -- 2.39.2