RE: [PATCH V2] mmc: debugfs: add error statistics

From: Sajida Bhanu (Temp) (QUIC)
Date: Wed Dec 29 2021 - 02:37:00 EST

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Gentle Reminder!!!

Thanks,
Sajida

-----Original Message-----
From: Sajida Bhanu (Temp) (QUIC) <quic_c_sbhanu@xxxxxxxxxxx>
Sent: Tuesday, December 21, 2021 12:46 PM
To: Adrian Hunter <adrian.hunter@xxxxxxxxx>; Sajida Bhanu (Temp) (QUIC) <quic_c_sbhanu@xxxxxxxxxxx>; riteshh@xxxxxxxxxxxxxx; Asutosh Das (asd) <asutoshd@xxxxxxxxxxx>; ulf.hansson@xxxxxxxxxx; agross@xxxxxxxxxx; bjorn.andersson@xxxxxxxxxx; linux-mmc@xxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Cc: stummala@xxxxxxxxxxxxxx; vbadigan@xxxxxxxxxxxxxx; Ram Prakash Gupta (QUIC) <quic_rampraka@xxxxxxxxxxx>; Pradeep Pragallapati (QUIC) <quic_pragalla@xxxxxxxxxxx>; sartgarg@xxxxxxxxxxxxxx; nitirawa@xxxxxxxxxxxxxx; sayalil@xxxxxxxxxxxxxx
Subject: RE: [PATCH V2] mmc: debugfs: add error statistics

Hi Adrian,

Thanks for the review.

Please find the inline comments.

Thanks,
Sajida

-----Original Message-----
From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Sent: Wednesday, December 15, 2021 7:33 PM
To: Sajida Bhanu (Temp) (QUIC) <quic_c_sbhanu@xxxxxxxxxxx>; riteshh@xxxxxxxxxxxxxx; Asutosh Das (asd) <asutoshd@xxxxxxxxxxx>; ulf.hansson@xxxxxxxxxx; agross@xxxxxxxxxx; bjorn.andersson@xxxxxxxxxx; linux-mmc@xxxxxxxxxxxxxxx; linux-arm-msm@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Cc: stummala@xxxxxxxxxxxxxx; vbadigan@xxxxxxxxxxxxxx; Ram Prakash Gupta (QUIC) <quic_rampraka@xxxxxxxxxxx>; Pradeep Pragallapati (QUIC) <quic_pragalla@xxxxxxxxxxx>; sartgarg@xxxxxxxxxxxxxx; nitirawa@xxxxxxxxxxxxxx; sayalil@xxxxxxxxxxxxxx
Subject: Re: [PATCH V2] mmc: debugfs: add error statistics

On 14/12/2021 16:41, Shaik Sajida Bhanu wrote:
> Add debugfs entry to query eMMC and SD card errors statistics.
> This feature is useful for debug and testing
>
> Signed-off-by: Shaik Sajida Bhanu <quic_c_sbhanu@xxxxxxxxxxx>
> ---
>
> Changes since V1:
> -Removed sysfs entry for eMMC and SD card error statistics and added
> debugfs entry as suggested by Adrian Hunter and Ulf Hansson.

Thanks for doing this.

> ---
> drivers/mmc/core/debugfs.c | 106 +++++++++++++++++++++++++++++++++++++++++++++
> drivers/mmc/core/queue.c | 2 +
> drivers/mmc/host/sdhci.c | 53 ++++++++++++++++++-----
> include/linux/mmc/host.h | 37 ++++++++++++++++
> 4 files changed, 186 insertions(+), 12 deletions(-)
>
> diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c
> index 3fdbc80..40210c34 100644
> --- a/drivers/mmc/core/debugfs.c
> +++ b/drivers/mmc/core/debugfs.c
> @@ -223,6 +223,107 @@ static int mmc_clock_opt_set(void *data, u64
> val) DEFINE_DEBUGFS_ATTRIBUTE(mmc_clock_fops, mmc_clock_opt_get, mmc_clock_opt_set,
> "%llu\n");
>
> +static int mmc_err_state_get(void *data, u64 *val) {
> + struct mmc_host *host = data;
> +
> + if (!host)
> + return -EINVAL;
> +
> + *val = host->err_state ? 1 : 0;
> +
> + return 0;
> +}
> +
> +static int mmc_err_state_clear(void *data, u64 val) {
> + struct mmc_host *host = data;
> +
> + if (!host)
> + return -EINVAL;
> +
> + host->err_state = false;

Is there much reason to disable err stats from userspace?

>>>>> Yes , while debugging we can go and check err_state , It is false means no errors happened in driver level and true means errors happened in driver level and then we can go and check err_stats[] to know more on error details like data CRC , command CRC etc.

> +
> + return 0;
> +}
> +
> +DEFINE_SIMPLE_ATTRIBUTE(mmc_err_state, mmc_err_state_get,
> + mmc_err_state_clear, "%llu\n");
> +
> +static int mmc_err_stats_show(struct seq_file *file, void *data) {
> + struct mmc_host *host = (struct mmc_host *)file->private;
> +
> + if (!host)
> + return -EINVAL;

I was thinking we needed a way to determine whether stats were being collected because not all drivers would support it at least initially e.g.

if (!host->err_stats_enabled) {
seq_printf(file, "Not supported by driver\n");
return 0;
}

>>>>>>>You mean declare another variable (err_stats_enabled) and enable it in probe?

> +
> + seq_printf(file, "# Command Timeout Occurred:\t %d\n",
> + host->err_stats[MMC_ERR_CMD_TIMEOUT]);

Maybe put the descriptions in an array and iterate e.g.

const char *desc[MMC_ERR_MAX] = {
[MMC_ERR_CMD_TIMEOUT] = "Command Timeout Occurred",
etc
};
int i;

if (!host)
return -EINVAL;

for (i = 0; i < MMC_ERR_MAX; i++) {
if (desc[i])
seq_printf(file, "# %s:\t %d\n",
desc[1], host->err_stats[i]);
}

>>>>>>> Sure

> +
> + seq_printf(file, "# Command CRC Errors Occurred:\t %d\n",
> + host->err_stats[MMC_ERR_CMD_CRC]);
> +
> + seq_printf(file, "# Data Timeout Occurred:\t %d\n",
> + host->err_stats[MMC_ERR_DAT_TIMEOUT]);
> +
> + seq_printf(file, "# Data CRC Errors Occurred:\t %d\n",
> + host->err_stats[MMC_ERR_DAT_CRC]);
> +
> + seq_printf(file, "# Auto-Cmd Error Occurred:\t %d\n",
> + host->err_stats[MMC_ERR_ADMA]);
> +
> + seq_printf(file, "# ADMA Error Occurred:\t %d\n",
> + host->err_stats[MMC_ERR_ADMA]);
> +
> + seq_printf(file, "# Tuning Error Occurred:\t %d\n",
> + host->err_stats[MMC_ERR_TUNING]);
> +
> + seq_printf(file, "# CMDQ RED Errors:\t\t %d\n",
> + host->err_stats[MMC_ERR_CMDQ_RED]);
> +
> + seq_printf(file, "# CMDQ GCE Errors:\t\t %d\n",
> + host->err_stats[MMC_ERR_CMDQ_GCE]);
> +
> + seq_printf(file, "# CMDQ ICCE Errors:\t\t %d\n",
> + host->err_stats[MMC_ERR_CMDQ_ICCE]);
> +
> + seq_printf(file, "# Request Timedout:\t %d\n",
> + host->err_stats[MMC_ERR_REQ_TIMEOUT]);
> +
> + seq_printf(file, "# CMDQ Request Timedout:\t %d\n",
> + host->err_stats[MMC_ERR_CMDQ_REQ_TIMEOUT]);
> +
> + seq_printf(file, "# ICE Config Errors:\t\t %d\n",
> + host->err_stats[MMC_ERR_ICE_CFG]);
> +
> + return 0;
> +}
> +
> +static int mmc_err_stats_open(struct inode *inode, struct file *file)
> +{
> + return single_open(file, mmc_err_stats_show, inode->i_private); }
> +
> +static ssize_t mmc_err_stats_write(struct file *filp, const char __user *ubuf,
> + size_t cnt, loff_t *ppos)
> +{
> + struct mmc_host *host = filp->f_mapping->host->i_private;
> +
> + if (!host)
> + return -EINVAL;
> +
> + pr_debug("%s: Resetting MMC error statistics\n", __func__);
> + memset(host->err_stats, 0, sizeof(host->err_stats));
> +
> + return cnt;
> +}
> +
> +static const struct file_operations mmc_err_stats_fops = {
> + .open = mmc_err_stats_open,
> + .read = seq_read,
> + .write = mmc_err_stats_write,
> +};
> +
> void mmc_add_host_debugfs(struct mmc_host *host) {
> struct dentry *root;
> @@ -236,6 +337,11 @@ void mmc_add_host_debugfs(struct mmc_host *host)
> debugfs_create_file_unsafe("clock", S_IRUSR | S_IWUSR, root, host,
> &mmc_clock_fops);
>
> + debugfs_create_file("err_state", 0600, root, host,
> + &mmc_err_state);
> + debugfs_create_file("err_stats", 0600, root, host,
> + &mmc_err_stats_fops);
> +
> #ifdef CONFIG_FAIL_MMC_REQUEST
> if (fail_request)
> setup_fault_attr(&fail_default_attr, fail_request); diff --git
> a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c index
> b15c034..5243929 100644
> --- a/drivers/mmc/core/queue.c
> +++ b/drivers/mmc/core/queue.c
> @@ -100,6 +100,8 @@ static enum blk_eh_timer_return mmc_cqe_timed_out(struct request *req)
> enum mmc_issue_type issue_type = mmc_issue_type(mq, req);
> bool recovery_needed = false;
>
> + mmc_debugfs_err_stats_inc(host, MMC_ERR_CMDQ_REQ_TIMEOUT);
> +
> switch (issue_type) {
> case MMC_ISSUE_ASYNC:
> case MMC_ISSUE_DCMD:
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c

I think the core changes should be a separate patch from sdhci.
I would probably split into 4:
mmc core
mmc block driver
cqhci driver
sdhci driver

>>>> Sure

> index 07c6da1..d742051 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -113,6 +113,7 @@ void sdhci_dumpregs(struct sdhci_host *host)
> if (host->ops->dump_vendor_regs)
> host->ops->dump_vendor_regs(host);
>
> + mmc_debugfs_err_stats_enable(host->mmc);

Why here and not in e.g. __sdhci_add_host() ?

>>>> If any errors happened in driver level then we will call sdhci_dumpregs() right( err_state true means some errors happened in driver level ). So it is better to call mmc_debugfs_err_stats_enable() here.

> SDHCI_DUMP("============================================\n");
> }
> EXPORT_SYMBOL_GPL(sdhci_dumpregs);
> @@ -3159,6 +3160,7 @@ static void sdhci_timeout_timer(struct timer_list *t)
> spin_lock_irqsave(&host->lock, flags);
>
> if (host->cmd && !sdhci_data_line_cmd(host->cmd)) {
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_REQ_TIMEOUT);
> pr_err("%s: Timeout waiting for hardware cmd interrupt.\n",
> mmc_hostname(host->mmc));
> sdhci_dumpregs(host);
> @@ -3181,6 +3183,7 @@ static void sdhci_timeout_data_timer(struct
> timer_list *t)
>
> if (host->data || host->data_cmd ||
> (host->cmd && sdhci_data_line_cmd(host->cmd))) {
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_REQ_TIMEOUT);
> pr_err("%s: Timeout waiting for hardware interrupt.\n",
> mmc_hostname(host->mmc));
> sdhci_dumpregs(host);
> @@ -3240,11 +3243,15 @@ static void sdhci_cmd_irq(struct sdhci_host
> *host, u32 intmask, u32 *intmask_p)
>
> if (intmask & (SDHCI_INT_TIMEOUT | SDHCI_INT_CRC |
> SDHCI_INT_END_BIT | SDHCI_INT_INDEX)) {
> - if (intmask & SDHCI_INT_TIMEOUT)
> + if (intmask & SDHCI_INT_TIMEOUT) {
> host->cmd->error = -ETIMEDOUT;
> - else
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_CMD_TIMEOUT);
> + } else {
> host->cmd->error = -EILSEQ;
> -
> + if (host->cmd->opcode != MMC_SEND_TUNING_BLOCK ||
> + host->cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200)
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_CMD_CRC);
> + }
> /* Treat data command CRC error the same as data CRC error */
> if (host->cmd->data &&
> (intmask & (SDHCI_INT_CRC | SDHCI_INT_TIMEOUT)) == @@ -3266,6
> +3273,7 @@ static void sdhci_cmd_irq(struct sdhci_host *host, u32
> +intmask, u32 *intmask_p)
> -ETIMEDOUT :
> -EILSEQ;
>
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_AUTO_CMD);
> if (sdhci_auto_cmd23(host, mrq)) {
> mrq->sbc->error = err;
> __sdhci_finish_mrq(host, mrq);
> @@ -3342,6 +3350,7 @@ static void sdhci_data_irq(struct sdhci_host *host, u32 intmask)
> if (intmask & SDHCI_INT_DATA_TIMEOUT) {
> host->data_cmd = NULL;
> data_cmd->error = -ETIMEDOUT;
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_CMD_TIMEOUT);
> __sdhci_finish_mrq(host, data_cmd->mrq);
> return;
> }
> @@ -3375,18 +3384,25 @@ static void sdhci_data_irq(struct sdhci_host *host, u32 intmask)
> return;
> }
>
> - if (intmask & SDHCI_INT_DATA_TIMEOUT)
> + if (intmask & SDHCI_INT_DATA_TIMEOUT) {
> host->data->error = -ETIMEDOUT;
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_DAT_TIMEOUT);
> + }
> else if (intmask & SDHCI_INT_DATA_END_BIT)
> host->data->error = -EILSEQ;
> else if ((intmask & SDHCI_INT_DATA_CRC) &&
> SDHCI_GET_CMD(sdhci_readw(host, SDHCI_COMMAND))
> - != MMC_BUS_TEST_R)
> + != MMC_BUS_TEST_R) {
> host->data->error = -EILSEQ;
> + if (host->cmd->opcode != MMC_SEND_TUNING_BLOCK ||
> + host->cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200)
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_DAT_CRC);
> + }
> else if (intmask & SDHCI_INT_ADMA_ERROR) {
> pr_err("%s: ADMA error: 0x%08x\n", mmc_hostname(host->mmc),
> intmask);
> sdhci_adma_show_error(host);
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_ADMA);
> host->data->error = -EIO;
> if (host->ops->adma_workaround)
> host->ops->adma_workaround(host, intmask); @@ -3905,20 +3921,33 @@
> bool sdhci_cqe_irq(struct sdhci_host *host, u32 intmask, int *cmd_error,
> if (!host->cqe_on)
> return false;
>
> - if (intmask & (SDHCI_INT_INDEX | SDHCI_INT_END_BIT | SDHCI_INT_CRC))
> + if (intmask & (SDHCI_INT_INDEX | SDHCI_INT_END_BIT | SDHCI_INT_CRC))
> +{
> *cmd_error = -EILSEQ;
> - else if (intmask & SDHCI_INT_TIMEOUT)
> + if (intmask & SDHCI_INT_CRC) {
> + if (host->cmd->opcode != MMC_SEND_TUNING_BLOCK ||
> + host->cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200)
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_CMD_CRC);
> + }
> + } else if (intmask & SDHCI_INT_TIMEOUT) {
> *cmd_error = -ETIMEDOUT;
> - else
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_CMD_TIMEOUT);
> + } else
> *cmd_error = 0;
>
> - if (intmask & (SDHCI_INT_DATA_END_BIT | SDHCI_INT_DATA_CRC))
> + if (intmask & (SDHCI_INT_DATA_END_BIT | SDHCI_INT_DATA_CRC)) {
> *data_error = -EILSEQ;
> - else if (intmask & SDHCI_INT_DATA_TIMEOUT)
> + if (intmask & SDHCI_INT_DATA_CRC) {
> + if (host->cmd->opcode != MMC_SEND_TUNING_BLOCK ||
> + host->cmd->opcode != MMC_SEND_TUNING_BLOCK_HS200)
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_DAT_CRC);
> + }
> + } else if (intmask & SDHCI_INT_DATA_TIMEOUT) {
> *data_error = -ETIMEDOUT;
> - else if (intmask & SDHCI_INT_ADMA_ERROR)
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_DAT_TIMEOUT);
> + } else if (intmask & SDHCI_INT_ADMA_ERROR) {
> *data_error = -EIO;
> - else
> + mmc_debugfs_err_stats_inc(host->mmc, MMC_ERR_ADMA);
> + } else
> *data_error = 0;
>
> /* Clear selected interrupts. */
> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h index
> 7afb57c..c263f8f 100644
> --- a/include/linux/mmc/host.h
> +++ b/include/linux/mmc/host.h
> @@ -93,6 +93,23 @@ struct mmc_clk_phase_map {
>
> struct mmc_host;
>
> +enum mmc_err_stat {
> + MMC_ERR_CMD_TIMEOUT,
> + MMC_ERR_CMD_CRC,
> + MMC_ERR_DAT_TIMEOUT,
> + MMC_ERR_DAT_CRC,
> + MMC_ERR_AUTO_CMD,
> + MMC_ERR_ADMA,
> + MMC_ERR_TUNING,
> + MMC_ERR_CMDQ_RED,
> + MMC_ERR_CMDQ_GCE,
> + MMC_ERR_CMDQ_ICCE,
> + MMC_ERR_REQ_TIMEOUT,
> + MMC_ERR_CMDQ_REQ_TIMEOUT,
> + MMC_ERR_ICE_CFG,
> + MMC_ERR_MAX,
> +};
> +
> struct mmc_host_ops {
> /*
> * It is optional for the host to implement pre_req and post_req in
> @@ -500,6 +517,8 @@ struct mmc_host {
>
> /* Host Software Queue support */
> bool hsq_enabled;
> + u32 err_stats[MMC_ERR_MAX];

If you make it u64 then we don't have to think about the value overflowing.

>>> Sure

> + bool err_state;
>
> unsigned long private[] ____cacheline_aligned;
> };
> @@ -635,6 +654,24 @@ static inline enum dma_data_direction mmc_get_dma_dir(struct mmc_data *data)
> return data->flags & MMC_DATA_WRITE ? DMA_TO_DEVICE :
> DMA_FROM_DEVICE; }
>
> +static inline void mmc_debugfs_err_stats_enable(struct mmc_host *mmc)
> +{
> + mmc->err_state = true;
> +}
> +
> +static inline void mmc_debugfs_err_stats_inc(struct mmc_host *mmc,
> + enum mmc_err_stat stat) {
> +
> + /*
> + * Ignore the command timeout errors observed during
> + * the card init as those are excepted.
> + */
> + if (!mmc->err_state)
> + mmc->err_stats[MMC_ERR_CMD_TIMEOUT] = 0;

This would be better handled in the card init code somewhere, not here.

>>>> Sure.

> +
> + mmc->err_stats[stat] += 1;
> +}
> +
> int mmc_send_tuning(struct mmc_host *host, u32 opcode, int
> *cmd_error); int mmc_send_abort_tuning(struct mmc_host *host, u32
> opcode); int mmc_get_ext_csd(struct mmc_card *card, u8
> **new_ext_csd);
>

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