mmc: mmc: Fix HS switch failure in mmc_select_hs400()
authorZiyuan Xu <xzy.xu@rock-chips.com>
Thu, 26 May 2016 05:50:32 +0000 (13:50 +0800)
committerUlf Hansson <ulf.hansson@linaro.org>
Mon, 25 Jul 2016 08:34:09 +0000 (10:34 +0200)
commit649c6059d2371fef886a8f967e21416204723d63
tree7915ac283672e0acf55916d41479365c36fa381c
parent987aa5f8059613bf85cbb6f64ffbd34f5cb7a9d1
mmc: mmc: Fix HS switch failure in mmc_select_hs400()

To slove the issue which was found on gru board for hs400.

[    4.616946] sdhci: Secure Digital Host Controller Interface driver
[    4.623135] sdhci: Copyright(c) Pierre Ossman
[    4.722575] sdhci-pltfm: SDHCI platform and OF driver helper
[    4.730962] sdhci-arasan fe330000.sdhci: No vmmc regulator found
[    4.737444] sdhci-arasan fe330000.sdhci: No vqmmc regulator found
[    4.774930] mmc0: SDHCI controller on fe330000.sdhci [fe330000.sdhci] using ADMA
[    4.980295] mmc0: switch to high-speed from hs200 failed, err:-84
[    4.986487] mmc0: error -84 whilst initialising MMC card

We should change HS400 mode selection timing to meet JEDEC
specification. The JEDEC 5.1 said that change the frequency to <= 52MHZ
after HS_TIMING switch. Refer to section 6.6.2.3 "HS400" timing mode
selection:
Set the "Timing Interface" parameter in the HS_TIMING[185] field of the
Extended CSD register to 0x1 to switch to High Speed mode and then set
the clock frequency to a value not greater than 52MHZ.

Signed-off-by: Ziyuan Xu <xzy.xu@rock-chips.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
drivers/mmc/core/mmc.c