Re: [PATCH V4 5/7] mmc: sdhci: add Auto CMD Auto Select support

From: Adrian Hunter
Date: Tue Jul 31 2018 - 04:07:23 EST

On 31/07/18 10:04, Chunyan Zhang wrote:
> Hi Adrian,
>
> On 30 July 2018 at 21:06, Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>> On 23/07/18 13:08, Chunyan Zhang wrote:
>>> As SD Host Controller Specification v4.10 documents:
>>> Host Controller Version 4.10 defines this "Auto CMD Auto Select" mode.
>>> Selection of Auto CMD depends on setting of CMD23 Enable in the Host
>>> Control 2 register which indicates whether card supports CMD23. If CMD23
>>> Enable =1, Auto CMD23 is used and if CMD23 Enable =0, Auto CMD12 is
>>> used. In case of Version 4.10 or later, use of Auto CMD Auto Select is
>>> recommended rather than use of Auto CMD12 Enable or Auto CMD23
>>> Enable.
>>>
>>> This patch add this new mode support.
>>>
>>> Signed-off-by: Chunyan Zhang <zhang.chunyan@xxxxxxxxxx>
>>> ---
>>> drivers/mmc/host/sdhci.c | 61 +++++++++++++++++++++++++++++++++++++++---------
>>> drivers/mmc/host/sdhci.h | 2 ++
>>> 2 files changed, 52 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>> index 5acea3d..5c60590 100644
>>> --- a/drivers/mmc/host/sdhci.c
>>> +++ b/drivers/mmc/host/sdhci.c
>>> @@ -311,6 +311,23 @@ static void sdhci_config_dma(struct sdhci_host *host)
>>> sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
>>> }
>>>
>>> +static void sdhci_enable_cmd23(struct sdhci_host *host)
>>> +{
>>> + u16 ctrl2;
>>> +
>>> + /*
>>> + * This is used along with "Auto CMD Auto Select" feature,
>>> + * which is introduced from v4.10, if card supports CMD23,
>>> + * Auto CMD23 should be used instead of Auto CMD12.
>>> + */
>>> + if (host->version >= SDHCI_SPEC_410 &&
>>> + (host->mmc->caps & MMC_CAP_CMD23)) {
>>
>> That is the host capability. It needs to be the card capability.
>
> Could you please elaborate the issue?
>
> I thought we're setting for host here. Do you mean we need to see the
> card capability?

Yes. SDHCI_TRNS_AUTO_SEL selects auto-CMD23 or auto-CMD12 based on this
setting, so this must reflect the card's capability.

>
>>
>>> + ctrl2 = sdhci_readw(host, SDHCI_HOST_CONTROL2);
>>> + ctrl2 |= SDHCI_CMD23_ENABLE;
>>> + sdhci_writew(host, ctrl2, SDHCI_HOST_CONTROL2);
>>> + }
>>> +}
>>> +
>>> static void sdhci_init(struct sdhci_host *host, int soft)
>>> {
>>> struct mmc_host *mmc = host->mmc;
>>> @@ -329,6 +346,8 @@ static void sdhci_init(struct sdhci_host *host, int soft)
>>> host->clock = 0;
>>> mmc->ops->set_ios(mmc, &mmc->ios);
>>> }
>>> +
>>> + sdhci_enable_cmd23(host);
>>> }
>>>
>>> static void sdhci_reinit(struct sdhci_host *host)
>>> @@ -1093,6 +1112,36 @@ static inline bool sdhci_auto_cmd12(struct sdhci_host *host,
>>> !mrq->cap_cmd_during_tfr;
>>> }
>>>
>>> +static inline void sdhci_auto_cmd_select(struct sdhci_host *host,
>>> + struct mmc_command *cmd,
>>> + u16 *mode)
>>> +{
>>> + bool use_cmd12 = sdhci_auto_cmd12(host, cmd->mrq) &&
>>> + (cmd->opcode != SD_IO_RW_EXTENDED);
>>> + bool use_cmd23 = cmd->mrq->sbc && (host->flags & SDHCI_AUTO_CMD23);
>>> +
>>> + /*
>>> + * In case of Version 4.10 or later, use of 'Auto CMD Auto
>>> + * Select' is recommended rather than use of 'Auto CMD12
>>> + * Enable' or 'Auto CMD23 Enable'.
>>> + */
>>> + if (host->version >= SDHCI_SPEC_410 && (use_cmd12 || use_cmd23)) {
>>> + *mode |= SDHCI_TRNS_AUTO_SEL;
>>
>> As noted in patch 4, the CMD23 argument is not just the block count for eMMC.
>
> Probably I haven't got your point...
>
>>From what I understand, auto_sel mode doesn't need argument2. Doesn't
> this work for eMMC?

CMD23 always needs an argument

>
> The test platform I used was just eMMC only, haven't found problem.

Because the bits that are missing from the CMD23 argument (reliable write,
context id, etc) will not make the command fail.

>
> Thanks,
> Chunyan
>
>>
>>> + return;
>>> + }
>>> +
>>> + /*
>>> + * If we are sending CMD23, CMD12 never gets sent
>>> + * on successful completion (so no Auto-CMD12).
>>> + */
>>> + if (use_cmd12) {
>>> + *mode |= SDHCI_TRNS_AUTO_CMD12;
>>> + } else if (use_cmd23) {
>>> + *mode |= SDHCI_TRNS_AUTO_CMD23;
>>> + sdhci_writel(host, cmd->mrq->sbc->arg, SDHCI_ARGUMENT2);
>>> + }
>>> +}
>>> +
>>> static void sdhci_set_transfer_mode(struct sdhci_host *host,
>>> struct mmc_command *cmd)
>>> {
>>> @@ -1119,17 +1168,7 @@ static void sdhci_set_transfer_mode(struct sdhci_host *host,
>>>
>>> if (mmc_op_multi(cmd->opcode) || data->blocks > 1) {
>>> mode = SDHCI_TRNS_BLK_CNT_EN | SDHCI_TRNS_MULTI;
>>> - /*
>>> - * If we are sending CMD23, CMD12 never gets sent
>>> - * on successful completion (so no Auto-CMD12).
>>> - */
>>> - if (sdhci_auto_cmd12(host, cmd->mrq) &&
>>> - (cmd->opcode != SD_IO_RW_EXTENDED))
>>> - mode |= SDHCI_TRNS_AUTO_CMD12;
>>> - else if (cmd->mrq->sbc && (host->flags & SDHCI_AUTO_CMD23)) {
>>> - mode |= SDHCI_TRNS_AUTO_CMD23;
>>> - sdhci_writel(host, cmd->mrq->sbc->arg, SDHCI_ARGUMENT2);
>>> - }
>>> + sdhci_auto_cmd_select(host, cmd, &mode);
>>> }
>>>
>>> if (data->flags & MMC_DATA_READ)
>>> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
>>> index 81aae07..a8f4ec2 100644
>>> --- a/drivers/mmc/host/sdhci.h
>>> +++ b/drivers/mmc/host/sdhci.h
>>> @@ -42,6 +42,7 @@
>>> #define SDHCI_TRNS_BLK_CNT_EN 0x02
>>> #define SDHCI_TRNS_AUTO_CMD12 0x04
>>> #define SDHCI_TRNS_AUTO_CMD23 0x08
>>> +#define SDHCI_TRNS_AUTO_SEL 0x0C
>>> #define SDHCI_TRNS_READ 0x10
>>> #define SDHCI_TRNS_MULTI 0x20
>>>
>>> @@ -185,6 +186,7 @@
>>> #define SDHCI_CTRL_DRV_TYPE_D 0x0030
>>> #define SDHCI_CTRL_EXEC_TUNING 0x0040
>>> #define SDHCI_CTRL_TUNED_CLK 0x0080
>>> +#define SDHCI_CMD23_ENABLE 0x0800
>>> #define SDHCI_CTRL_V4_MODE 0x1000
>>> #define SDHCI_CTRL_64BIT_ADDR 0x2000
>>> #define SDHCI_CTRL_PRESET_VAL_ENABLE 0x8000
>>>
>>
>