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

Adrian Hunter
2017-08-17T06:38:19Z

On 17/08/17 08:20, Kishon Vijay Abraham I wrote:
> 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@ti.com>
>>> ---
>>> 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.

Except that it is the way I described. All the others strip the CRC and we
have to shift to pretend it is still there.

>
>>
>>> + /*
>>> + * 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
>