Re: [RFC PATCH 1/7] mmc: sdhci: Add quirk to indicate no CRC stripping in MMC_RSP_136

Kishon Vijay Abraham I
2017-08-17T05:20:38Z

Hi Adrian,

On Tuesday 15 August 2017 12:57 PM, Adrian Hunter wrote:
> On 07/08/17 19:01, Kishon Vijay Abraham I wrote:
>> TI's implementation of sdhci controller used in DRA7 SoC's doesn't
>> strip CRC in responses with length 136 bits. Add quirk to indicate
>> the controller does not strip CRC in MMC_RSP_136. If this quirk is
>> set sdhci library shouldn't shift the response present in
>> SDHCI_RESPONSE register.
>>
>> Signed-off-by: Kishon Vijay Abraham I <kishon-l0cyMroinI0@public.gmane.org>
>> ---
>> drivers/mmc/host/sdhci.c | 27 +++++++++++++++++++--------
>> drivers/mmc/host/sdhci.h | 2 ++
>> 2 files changed, 21 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index ecd0d4350e8a..ece3751d2a25 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -1182,14 +1182,25 @@ static void sdhci_finish_command(struct sdhci_host *host)
>>
>> if (cmd->flags & MMC_RSP_PRESENT) {
>> if (cmd->flags & MMC_RSP_136) {
>> - /* CRC is stripped so we need to do some shifting. */
>> - for (i = 0;i < 4;i++) {
>> - cmd->resp[i] = sdhci_readl(host,
>> - SDHCI_RESPONSE + (3-i)*4) << 8;
>> - if (i != 3)
>> - cmd->resp[i] |=
>> - sdhci_readb(host,
>> - SDHCI_RESPONSE + (3-i)*4-1);
>> + if (!(host->quirks2 & SDHCI_QUIRK2_NO_CRC_STRIPPING)) {
>
> This is about the 136-bit response so let's put that in the quirk name. How about SDHCI_QUIRK2_RSP_136_HAS_CRC

Since omap seems to be the only platform that doesn't have CRC, I prefer adding
SDHCI_QUIRK2_RSP_136_NO_CRC. That way we can add the quirk only in sdhci-omap
instead of all the existing sdhci drivers.

>
>> + /*
>> + * CRC is stripped so we need to do some
>> + * shifting.
>> + */
>> + for (i = 0; i < 4; i++) {
>> + cmd->resp[i] =
>> + sdhci_readl(host, SDHCI_RESPONSE
>> + + (3 - i) * 4) << 8;
>> + if (i != 3)
>> + cmd->resp[i] |=
>> + sdhci_readb(host, SDHCI_RESPONSE
>> + + (3 - i) * 4 - 1);
>> + }
>> + } else {
>> + for (i = 0; i < 4; i++)
>> + cmd->resp[i] =
>> + sdhci_readl(host, SDHCI_RESPONSE +
>> + (3 - i) * 4);
>> }
>
> This is all very jammed up against the 80 column margin. Please make a new patch to separate it into a new function sdhci_read_rsp_136() and then another patch to add the quirk.
> i.e. completely untested!

Sure. Thanks for the patch.

Thanks
Kishon
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