Hi Wolfram-san,
Thank you for the patch!
> From: Wolfram Sang, Sent: Wednesday, April 22, 2020 9:59 PM
> To: linux-mmc@xxxxxxxxxxxxxxx
> Cc: linux-renesas-soc@xxxxxxxxxxxxxxx; Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>; Takeshi Saito
> <takeshi.saito.xv@xxxxxxxxxxx>; Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
> Subject: [PATCH 2/2] mmc: renesas_sdhi: avoid bad TAP in HS400
>
> From: Takeshi Saito <takeshi.saito.xv@xxxxxxxxxxx>
>
> With R-Car Gen3, CRC error occue at the following TAPs.
>
> H3, M3W 1.3, M3N... TAP=2,3,6,7
> M3W 3.0 ... TAP=1,3,5,7
>
> (Note: for 4tap SoCs, the numbers get divided by 2)
>
> Do not use these TAPs in HS400, and also don't use auto correction but
> manual correction.
>
> We check for bad taps in two places:
>
> 1) After tuning HS400: Then, we select a neighbouring TAP. One of them
> must be good, because there are never three bad taps in a row.
> Retuning won't help because we just finished tuning.
>
> 2) After a manual correction request: Here, we can't switch to the
> requested TAP. But we can retune (if the HS200 tuning was good)
> because the environment might have changed since the last tuning.
> If not, we stay on the same TAP.
>
> Signed-off-by: Takeshi Saito <takeshi.saito.xv@xxxxxxxxxxx>
> [wsa: refactored to match upstream driver, reworded commit msg]
> Signed-off-by: Wolfram Sang <wsa+renesas@xxxxxxxxxxxxxxxxxxxx>
> ---
> drivers/mmc/host/renesas_sdhi.h | 1 +
> drivers/mmc/host/renesas_sdhi_core.c | 56 ++++++++++++++++++++++++----
> 2 files changed, 49 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/mmc/host/renesas_sdhi.h b/drivers/mmc/host/renesas_sdhi.h
> index 86efa9d5cd6d..14c64caefc64 100644
> --- a/drivers/mmc/host/renesas_sdhi.h
> +++ b/drivers/mmc/host/renesas_sdhi.h
> @@ -36,6 +36,7 @@ struct renesas_sdhi_of_data {
> struct renesas_sdhi_quirks {
> bool hs400_disabled;
> bool hs400_4taps;
> + u32 hs400_bad_taps;
> };
>
> struct tmio_mmc_dma {
> diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
> index 33b51105c788..4fee26e6b66c 100644
> --- a/drivers/mmc/host/renesas_sdhi_core.c
> +++ b/drivers/mmc/host/renesas_sdhi_core.c
> @@ -325,6 +325,8 @@ static void renesas_sdhi_hs400_complete(struct mmc_host *mmc)
> {
> struct tmio_mmc_host *host = mmc_priv(mmc);
> struct renesas_sdhi *priv = host_to_priv(host);
> + u32 bad_taps = priv->quirks ? priv->quirks->hs400_bad_taps : 0;
> + bool use_4tap = priv->quirks && priv->quirks->hs400_4taps;
>
> sd_ctrl_write16(host, CTL_SD_CARD_CLK_CTL, ~CLK_CTL_SCLKEN &
> sd_ctrl_read16(host, CTL_SD_CARD_CLK_CTL));
> @@ -352,10 +354,24 @@ static void renesas_sdhi_hs400_complete(struct mmc_host *mmc)
> SH_MOBILE_SDHI_SCC_DTCNTL_TAPEN |
> 0x4 << SH_MOBILE_SDHI_SCC_DTCNTL_TAPNUM_SHIFT);
>
> + /* Avoid bad TAP */
> + if (bad_taps & BIT(priv->tap_set)) {
> + u32 new_tap = (priv->tap_set + 1) % priv->tap_num;
> +
> + if (bad_taps & BIT(new_tap)) {
> + new_tap = (priv->tap_set - 1) % priv->tap_num;
> + }
I think we can remove the braces.
After removed it,
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@xxxxxxxxxxx>
Best regards,
Yoshihiro Shimoda
