RE: [RFC PATCH v2 3/5] mmc: renesas_sdhi: only check CMD status for HS400 manual correction

[Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>]

Hi Wolfram-san,

> From: Wolfram Sang, Sent: Tuesday, December 17, 2019 8:41 PM
> 
> R-Car Gen3 cannot use correction error status with HS400.
> HS200: CMD and DAT signal timing are based on CLK signal.
> HS400: CMD signal is based on CLK. DAT signal is based on DS signal.
> 
> In HS400, CMD signal is 200MHz(SDR). DAT signal is 200MHz(DDR).
> Center position of signal is different between CMD and DAT.
> 
> TAP position should be adjusted to the center position of CMD signal.
> DAT sampling timing is adjusted by HS400 calibration circuit regardless
> of TAP position. Refer to renesas_sdhi_adjust_hs400mode_enable().
> 
> However, correction error status contains CMD and DAT status in HS400
> (DAT signal is not masked in HS400). Therefore, correction error status
> cannot use in HS400. It means that auto correction cannot be uses in
> HS400. Manual correction can change to the correct TAP position by
> ignoring DAT correction error status and using only CMD correction
> status.
> 
> Signed-off-by: Takeshi Saito <takeshi.saito.xv@renesas.com>
> [wsa: refactored patch from BSP]
> Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>

Thank you for the patch!

Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

Best regards,
Yoshihiro Shimoda