On 26/05/16 08:50, Ziyuan Xu wrote:
> 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.
Do you need a fix also for re-tuning? i.e. does re-tuning work with this
patch? Or do you not need re-tuning?
>
> Signed-off-by: Ziyuan Xu <xzy.xu@xxxxxxxxxxxxxx>
> ---
> drivers/mmc/core/mmc.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
> index b81b08f..8e4d059 100644
> --- a/drivers/mmc/core/mmc.c
> +++ b/drivers/mmc/core/mmc.c
> @@ -1078,10 +1078,6 @@ static int mmc_select_hs400(struct mmc_card *card)
> if (host->caps & MMC_CAP_WAIT_WHILE_BUSY)
> send_status = false;
>
> - /* Reduce frequency to HS frequency */
> - max_dtr = card->ext_csd.hs_max_dtr;
> - mmc_set_clock(host, max_dtr);
> -
> /* Switch card to HS mode */
> val = EXT_CSD_TIMING_HS;
> err = __mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
> @@ -1097,6 +1093,10 @@ static int mmc_select_hs400(struct mmc_card *card)
> /* Set host controller to HS timing */
> mmc_set_timing(card->host, MMC_TIMING_MMC_HS);
>
> + /* Reduce frequency to HS frequency */
> + max_dtr = card->ext_csd.hs_max_dtr;
> + mmc_set_clock(host, max_dtr);
> +
> if (!send_status) {
> err = mmc_switch_status(card);
> if (err)
>
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