Re: [PATCH V16 08/23] mmc: core: Support UHS-II Auto Command Error Recovery

From: Victor Shih
Date: Sun Jun 09 2024 - 14:40:29 EST

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On Fri, May 31, 2024 at 7:23 PM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
>
> On 31/05/24 13:31, Victor Shih wrote:
> > On Fri, May 24, 2024 at 2:54 PM Adrian Hunter <adrian.hunter@xxxxxxxxx> wrote:
> >>
> >> On 22/05/24 14:08, Victor Shih wrote:
> >>> From: Victor Shih <victor.shih@xxxxxxxxxxxxxxxxxxx>
> >>>
> >>> Add UHS-II Auto Command Error Recovery functionality
> >>> into the MMC request processing flow.
> >>
> >> Not sure what "auto" means here, but the commit message
> >> should outline what the spec. requires for error recovery.
> >>
> >
> > Hi, Adrian
> >
> > I will add instructions in the v17 version.
> >
> > Thanks, Victor Shih
> >
> >>>
> >>> Signed-off-by: Ben Chuang <ben.chuang@xxxxxxxxxxxxxxxxxxx>
> >>> Signed-off-by: Victor Shih <victor.shih@xxxxxxxxxxxxxxxxxxx>
> >>> ---
> >>>
> >>> Updates in V16:
> >>> - Separate the Error Recovery mechanism from patch#7 to patch#8.
> >>>
> >>> ---
> >>>
> >>> drivers/mmc/core/core.c | 4 ++
> >>> drivers/mmc/core/core.h | 1 +
> >>> drivers/mmc/core/sd_uhs2.c | 80 ++++++++++++++++++++++++++++++++++++++
> >>> include/linux/mmc/host.h | 6 +++
> >>> 4 files changed, 91 insertions(+)
> >>>
> >>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> >>> index 68496c51a521..18642afc405f 100644
> >>> --- a/drivers/mmc/core/core.c
> >>> +++ b/drivers/mmc/core/core.c
> >>> @@ -403,6 +403,10 @@ void mmc_wait_for_req_done(struct mmc_host *host, struct mmc_request *mrq)
> >>> while (1) {
> >>> wait_for_completion(&mrq->completion);
> >>>
> >>> + if (host->ops->get_cd(host))
> >>> + if (mrq->cmd->error || (mrq->data && mrq->data->error))
> >>> + mmc_sd_uhs2_error_recovery(host, mrq);
> >>
> >> There are several issues with this:
> >>
> >> 1. It is not OK to start a request from within the request path
> >> because it is recursive:
> >>
> >> mmc_wait_for_req_done() <--
> >> mmc_sd_uhs2_error_recovery()
> >> sd_uhs2_abort_trans()
> >> mmc_wait_for_cmd()
> >> mmc_wait_for_req()
> >> mmc_wait_for_req_done() <--
> >>
> >> 2. The mmc block driver does not use this path
> >>
> >> 3. No need to always call ->get_cd() if there is no error
> >>
> >> It is worth considering whether the host controller could
> >> send the abort command as part of the original request, as
> >> is done with the stop command.
> >>
> >
> > Hi, Adrian
> >
> > 1. It looks like just issuing a command in
> > mmc_wait_for_req_done() will cause a recursion.
> > I will drop sd_uhs2_abort_trans() and
> > sd_uhs2_abort_status_read() in the v17 version.
> > 2. I have no idea about this part, could you please give me some advice?
>
> The mmc block driver sets the ->done() callback and so
> mmc_wait_for_req_done() is never called for data transfers.
>
> That won't matter if the host controller handles doing
> the abort command, as was suggested elsewhere.
>
> > 3. I will try to modify this part in the v17 version.
> >
> > Thanks, Victor Shih
> >
> >>> +
> >>> cmd = mrq->cmd;
> >>>
> >>> if (!cmd->error || !cmd->retries ||
> >>> diff --git a/drivers/mmc/core/core.h b/drivers/mmc/core/core.h
> >>> index 920323faa834..259d47c8bb19 100644
> >>> --- a/drivers/mmc/core/core.h
> >>> +++ b/drivers/mmc/core/core.h
> >>> @@ -82,6 +82,7 @@ int mmc_attach_mmc(struct mmc_host *host);
> >>> int mmc_attach_sd(struct mmc_host *host);
> >>> int mmc_attach_sdio(struct mmc_host *host);
> >>> int mmc_attach_sd_uhs2(struct mmc_host *host);
> >>> +void mmc_sd_uhs2_error_recovery(struct mmc_host *mmc, struct mmc_request *mrq);
> >>>
> >>> /* Module parameters */
> >>> extern bool use_spi_crc;
> >>> diff --git a/drivers/mmc/core/sd_uhs2.c b/drivers/mmc/core/sd_uhs2.c
> >>> index 85939a2582dc..d5acb4e6ccac 100644
> >>> --- a/drivers/mmc/core/sd_uhs2.c
> >>> +++ b/drivers/mmc/core/sd_uhs2.c
> >>> @@ -1324,3 +1324,83 @@ int mmc_attach_sd_uhs2(struct mmc_host *host)
> >>>
> >>> return err;
> >>> }
> >>> +
> >>> +static void sd_uhs2_abort_trans(struct mmc_host *mmc)
> >>> +{
> >>> + struct mmc_request mrq = {};
> >>> + struct mmc_command cmd = {0};
> >>> + struct uhs2_command uhs2_cmd = {};
> >>> + int err;
> >>> +
> >>> + mrq.cmd = &cmd;
> >>> + mmc->ongoing_mrq = &mrq;
> >>> +
> >>> + uhs2_cmd.header = UHS2_NATIVE_PACKET | UHS2_PACKET_TYPE_CCMD |
> >>> + mmc->card->uhs2_config.node_id;
> >>> + uhs2_cmd.arg = ((UHS2_DEV_CMD_TRANS_ABORT & 0xFF) << 8) |
> >>> + UHS2_NATIVE_CMD_WRITE |
> >>> + (UHS2_DEV_CMD_TRANS_ABORT >> 8);
> >>> +
> >>> + sd_uhs2_cmd_assemble(&cmd, &uhs2_cmd, 0, 0);
> >>> + err = mmc_wait_for_cmd(mmc, &cmd, 0);
> >>> +
> >>> + if (err)
> >>> + pr_err("%s: %s: UHS2 CMD send fail, err= 0x%x!\n",
> >>> + mmc_hostname(mmc), __func__, err);
> >>> +}
> >>> +
> >>> +static void sd_uhs2_abort_status_read(struct mmc_host *mmc)
> >>> +{
> >>> + struct mmc_request mrq = {};
> >>> + struct mmc_command cmd = {0};
> >>> + struct uhs2_command uhs2_cmd = {};
> >>> + int err;
> >>> +
> >>> + mrq.cmd = &cmd;
> >>> + mmc->ongoing_mrq = &mrq;
> >>> +
> >>> + uhs2_cmd.header = UHS2_NATIVE_PACKET |
> >>> + UHS2_PACKET_TYPE_CCMD |
> >>> + mmc->card->uhs2_config.node_id;
> >>> + uhs2_cmd.arg = ((UHS2_DEV_STATUS_REG & 0xFF) << 8) |
> >>> + UHS2_NATIVE_CMD_READ |
> >>> + UHS2_NATIVE_CMD_PLEN_4B |
> >>> + (UHS2_DEV_STATUS_REG >> 8);
> >>> +
> >>> + sd_uhs2_cmd_assemble(&cmd, &uhs2_cmd, 0, 0);
> >>> + err = mmc_wait_for_cmd(mmc, &cmd, 0);
> >>> +
> >>> + if (err)
> >>> + pr_err("%s: %s: UHS2 CMD send fail, err= 0x%x!\n",
> >>> + mmc_hostname(mmc), __func__, err);
> >>> +}
> >>> +
> >>> +void mmc_sd_uhs2_error_recovery(struct mmc_host *mmc, struct mmc_request *mrq)
> >>> +{
> >>> + mmc->ops->uhs2_reset_cmd_data(mmc);
> >>
> >> The host controller should already have done any resets needed.
> >> sdhci already has support for doing that - see host->pending_reset
> >>
> >
> > Hi, Adrian
> >
> > I'm not sure what this means. Could you please give me more information?
>
> sdhci_uhs2_request_done() checks sdhci_needs_reset() and does
> sdhci_uhs2_reset().
>
> sdhci_needs_reset() does not cater for data errors because
> the reset for data errors is done directly in what becomes
> __sdhci_finish_data_common().
>
> You may need to:
> 1. add a parameter to __sdhci_finish_data_common() to
> skip doing the sdhci reset and instead set
> host->pending_reset
> 2. amend sdhci_uhs2_request_done() to check for data error
> also to decide if a reset is needed
>

Hi, Adrian

If there is any mistake in my understanding, please help me correct it.
My understanding is as follows:

static bool sdhci_uhs2_request_done(struct sdhci_host *host)
{
...
if (sdhci_needs_reset(host, mrq)) {
...
if (mrq->cmd->error || (mrq->data && mrq->data->error))
sdhci_uhs2_reset_cmd_data(host->mmc);
...
}
...
}

I have another question. the sdhci_uhs2_request_done() belongs to the patch#18.
Can the above content be modified directly in the patch#18?
Or does it need to be separated into another patch?

Thanks, Victor Shih

> >
> > Thanks, Victor Shih
> >
> >>> +
> >>> + if (mrq->data) {
> >>> + if (mrq->data->error && mmc_card_uhs2(mmc)) {
> >>> + if (mrq->cmd) {
> >>> + switch (mrq->cmd->error) {
> >>> + case ETIMEDOUT:
> >>> + case EILSEQ:
> >>> + case EIO:
> >>> + sd_uhs2_abort_trans(mmc);
> >>> + sd_uhs2_abort_status_read(mmc);
> >>
> >> What is the purpose of sd_uhs2_abort_status_read() here?
> >> It is not obvious it does anything.
> >>
> >
> > Hi, Adrian
> >
> > sd_uhs2_abort_status_read() seems to only have read status,
> > I will drop this in the v17 version.
> >
> > Thanks, Victor Shih
> >
> >>> + break;
> >>> + default:
> >>> + break;
> >>> + }
> >>> + }
> >>> + }
> >>> + } else {
> >>> + if (mrq->cmd) {
> >>> + switch (mrq->cmd->error) {
> >>> + case ETIMEDOUT:
> >>> + sd_uhs2_abort_trans(mmc);
> >>> + break;
> >>> + }
> >>> + }
> >>> + }
> >>> +}
> >>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
> >>> index fc9520b3bfa4..c914a58f7e1e 100644
> >>> --- a/include/linux/mmc/host.h
> >>> +++ b/include/linux/mmc/host.h
> >>> @@ -271,6 +271,12 @@ struct mmc_host_ops {
> >>> * negative errno in case of a failure or zero for success.
> >>> */
> >>> int (*uhs2_control)(struct mmc_host *host, enum sd_uhs2_operation op);
> >>> +
> >>> + /*
> >>> + * The uhs2_reset_cmd_data callback is used to excute reset
> >>> + * when a auto command error occurs.
> >>> + */
> >>> + void (*uhs2_reset_cmd_data)(struct mmc_host *host);
> >>> };
> >>>
> >>> struct mmc_cqe_ops {
> >>
>

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