From 5b0edb353a0eab4abd466682b7099147a3d573f0 Mon Sep 17 00:00:00 2001 From: xiaoyao Date: Thu, 22 Sep 2016 17:21:24 +0800 Subject: [PATCH] mmc: core: changes frequency to hs_max_dtr when selecting hs400es Per JESD84-B51 P69, Host need to change frequency to <=52MHz after setting HS_TIMING to 0x1, and host may changes frequency to <= 200MHz after setting HS_TIMING to 0x3. It seems there is no difference if we don't change frequency to <= 52MHz as f_init is already less than 52MHz. But actually it does make difference. When doing compatibility test we see failures for some eMMC devices without changing the frequency to hs_max_dtr. And let's read the spec again, we could see that "Host may changes frequency to 200MHz" implies that it's not mandatory. But the "Host need to change frequency to <= 52MHz" implies that we should do this. Change-Id: I1dc9f5fa8dc217e033fc4b1689ca1b0204c294c0 Signed-off-by: Shawn Lin Signed-off-by: xiaoyao --- drivers/mmc/core/mmc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c index ed5d54dd7c4e..3c2c026f66cd 100644 --- a/drivers/mmc/core/mmc.c +++ b/drivers/mmc/core/mmc.c @@ -1266,6 +1266,8 @@ static int mmc_select_hs400es(struct mmc_card *card) if (err) goto out_err; + mmc_set_clock(host, card->ext_csd.hs_max_dtr); + err = mmc_switch_status(card); if (err) goto out_err; -- 2.34.1