Re: [PATCH V8 06/23] mmc: core: Support UHS-II card control and access

[Adrian Hunter]

On 19/07/23 13:24, Victor Shih wrote:
> On Mon, Jul 10, 2023 at 9:24 PM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>>
>> On 21/06/23 13:01, Victor Shih wrote:
>>> From: Victor Shih <victor.shih@xxxxxxxxxxxxxxxxxxx>
>>>
>>> Embed UHS-II access/control functionality into the MMC request
>>> processing flow.
>>>
>>> Updates in V8:
>>>  - Add MMC_UHS2_SUPPORT to be cleared in sd_uhs2_detect().
>>>  - Modify return value in sd_uhs2_attach().
>>>
>>> Updates in V7:
>>>  - Add mmc_uhs2_card_prepare_cmd helper function in sd_ops.h.
>>>  - Drop uhs2_state in favor of ios->timing.
>>>  - Remove unnecessary functions.
>>>
>>> Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx>
>>> Signed-off-by: Jason Lai <jason.lai@xxxxxxxxxxxxxxxxxxx>
>>> Signed-off-by: Victor Shih <victor.shih@xxxxxxxxxxxxxxxxxxx>
>>> ---
>>>  drivers/mmc/core/block.c   |   18 +-
>>>  drivers/mmc/core/core.c    |    8 +
>>>  drivers/mmc/core/mmc_ops.c |   25 +-
>>>  drivers/mmc/core/mmc_ops.h |    1 +
>>>  drivers/mmc/core/sd.c      |   13 +-
>>>  drivers/mmc/core/sd.h      |    4 +
>>>  drivers/mmc/core/sd_ops.c  |   11 +
>>>  drivers/mmc/core/sd_ops.h  |   18 +
>>>  drivers/mmc/core/sd_uhs2.c | 1137 +++++++++++++++++++++++++++++++++++-
>>>  9 files changed, 1176 insertions(+), 59 deletions(-)
>>>
>>> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
>>> index 2e9d3760c202..013ab071db9b 100644
>>> --- a/drivers/mmc/core/block.c
>>> +++ b/drivers/mmc/core/block.c
>>> @@ -918,15 +918,9 @@ static int mmc_sd_num_wr_blocks(struct mmc_card *card, u32 *written_blocks)
>>>
>>>       struct scatterlist sg;
>>>
>>> -     cmd.opcode = MMC_APP_CMD;
>>> -     cmd.arg = card->rca << 16;
>>> -     cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_AC;
>>> -
>>> -     err = mmc_wait_for_cmd(card->host, &cmd, 0);
>>> -     if (err)
>>> -             return err;
>>> -     if (!mmc_host_is_spi(card->host) && !(cmd.resp[0] & R1_APP_CMD))
>>> -             return -EIO;
>>> +     err = mmc_app_cmd(card->host, card);
>>> +             if (err)
>>> +                     return err;
>>>
>>>       memset(&cmd, 0, sizeof(struct mmc_command));
>>>
>>> @@ -1612,6 +1606,9 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
>>>       struct request *req = mmc_queue_req_to_req(mqrq);
>>>       struct mmc_blk_data *md = mq->blkdata;
>>>       bool do_rel_wr, do_data_tag;
>>> +     bool do_multi;
>>> +
>>> +     do_multi = (card->host->flags & MMC_UHS2_SD_TRAN) ? true : false;
>>>
>>>       mmc_blk_data_prep(mq, mqrq, recovery_mode, &do_rel_wr, &do_data_tag);
>>>
>>> @@ -1622,7 +1619,7 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
>>>               brq->cmd.arg <<= 9;
>>>       brq->cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_R1 | MMC_CMD_ADTC;
>>>
>>> -     if (brq->data.blocks > 1 || do_rel_wr) {
>>> +     if (brq->data.blocks > 1 || do_rel_wr || do_multi) {
>>>               /* SPI multiblock writes terminate using a special
>>>                * token, not a STOP_TRANSMISSION request.
>>>                */
>>> @@ -1635,6 +1632,7 @@ static void mmc_blk_rw_rq_prep(struct mmc_queue_req *mqrq,
>>>               brq->mrq.stop = NULL;
>>>               readcmd = MMC_READ_SINGLE_BLOCK;
>>>               writecmd = MMC_WRITE_BLOCK;
>>> +             brq->cmd.uhs2_tmode0_flag = 1;
>>>       }
>>>       brq->cmd.opcode = rq_data_dir(req) == READ ? readcmd : writecmd;
>>>
>>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>>> index 7b8227e7ed26..04783f37da92 100644
>>> --- a/drivers/mmc/core/core.c
>>> +++ b/drivers/mmc/core/core.c
>>> @@ -334,6 +334,8 @@ static int mmc_mrq_prep(struct mmc_host *host, struct mmc_request *mrq)
>>>
>>>  int mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
>>>  {
>>> +     struct uhs2_command uhs2_cmd;
>>> +     __be32 payload[4]; /* for maximum size */
>>>       int err;
>>>
>>>       init_completion(&mrq->cmd_completion);
>>> @@ -351,6 +353,8 @@ int mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
>>>       if (err)
>>>               return err;
>>>
>>> +     mmc_uhs2_card_prepare_cmd(host, mrq, uhs2_cmd, payload);
>>> +
>>>       led_trigger_event(host->led, LED_FULL);
>>>       __mmc_start_request(host, mrq);
>>
>> __mmc_start_request() is also called by mmc_wait_for_req_done()
>> but uhs2_cmd is local to mmc_start_request(), so if mmc_wait_for_req_done()
>> is ever called in UHS2 case with cmd->retries, it looks like
>> host controller might try to access uhs2_cmd which is no
>> longer valid?
>>
>>
> 
> Hi, Adrian
> 
>       I traced the code between the SD card initialization process and
> found that
>       __mmc_start_request() is only called by mmc_start_request in the
> UHS2 case.
>       I'm not sure if there's anything I'm missing, could you help me
> with more comments?

Perhaps mmc_send_status() used in block.c ?

>       Or may you have any ideas on how to avoid this situation?
> 

Need to get Ulf's view, but putting "struct uhs2_command uhs2_cmd"
and "__be32 payload[4]" in struct mmc_command or struct mmc_request
would seem to be options.  If size is a concern, some optimization
to reduce the size of struct uhs2_command looks possible, and is
max payload len actually only 2 at the moment.