Re: [PATCH v1 2/2] scsi: ufs: Try to save power mode change and UIC cmd completion timeout

[Stanley Chu]

Hi Can,

Except for below nit, otherwise looks good to me.

Reviewed-by: Stanley Chu <stanley.chu@xxxxxxxxxxxx>

On Mon, 2020-11-02 at 22:24 -0800, Can Guo wrote:
> Use the uic_cmd->cmd_active as a flag to track the lifecycle of an UIC cmd.
> The flag is set before send the UIC cmd and cleared in IRQ handler. When a
> PMC or UIC cmd completion timeout happens, if the flag is not set, instead
> of returning timeout error, we still treat it as a successful operation.
> This is to deal with the scenario in which completion has been raised but
> the one waiting for the completion cannot be awaken in time due to kernel
> scheduling problem.
> 
> Signed-off-by: Can Guo <cang@xxxxxxxxxxxxxx>
> ---
>  drivers/scsi/ufs/ufshcd.c | 26 ++++++++++++++++++++++++--
>  drivers/scsi/ufs/ufshcd.h |  2 ++
>  2 files changed, 26 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
> index efa7d86..7f33310 100644
> --- a/drivers/scsi/ufs/ufshcd.c
> +++ b/drivers/scsi/ufs/ufshcd.c
> @@ -2122,10 +2122,20 @@ ufshcd_wait_for_uic_cmd(struct ufs_hba *hba, struct uic_command *uic_cmd)
>  	unsigned long flags;
>  
>  	if (wait_for_completion_timeout(&uic_cmd->done,
> -					msecs_to_jiffies(UIC_CMD_TIMEOUT)))
> +					msecs_to_jiffies(UIC_CMD_TIMEOUT))) {
>  		ret = uic_cmd->argument2 & MASK_UIC_COMMAND_RESULT;
> -	else
> +	} else {
>  		ret = -ETIMEDOUT;
> +		dev_err(hba->dev,
> +			"uic cmd 0x%x with arg3 0x%x completion timeout\n",
> +			uic_cmd->command, uic_cmd->argument3);
> +
> +		if (!uic_cmd->cmd_active) {
> +			dev_err(hba->dev, "%s: UIC cmd has been completed, return the result\n",
> +				__func__);
> +			ret = uic_cmd->argument2 & MASK_UIC_COMMAND_RESULT;
> +		}
> +	}
>  
>  	spin_lock_irqsave(hba->host->host_lock, flags);
>  	hba->active_uic_cmd = NULL;
> @@ -2157,6 +2167,7 @@ __ufshcd_send_uic_cmd(struct ufs_hba *hba, struct uic_command *uic_cmd,
>  	if (completion)
>  		init_completion(&uic_cmd->done);
>  
> +	uic_cmd->cmd_active = 1;
>  	ufshcd_dispatch_uic_cmd(hba, uic_cmd);
>  
>  	return 0;
> @@ -3828,10 +3839,18 @@ static int ufshcd_uic_pwr_ctrl(struct ufs_hba *hba, struct uic_command *cmd)
>  		dev_err(hba->dev,
>  			"pwr ctrl cmd 0x%x with mode 0x%x completion timeout\n",
>  			cmd->command, cmd->argument3);
> +
> +		if (!cmd->cmd_active) {
> +			dev_err(hba->dev, "%s: Power Mode Change operation has been completed, go check UPMCRS\n",
> +				__func__);
> +			goto check_upmcrs;
> +		}
> +
>  		ret = -ETIMEDOUT;
>  		goto out;
>  	}
>  
> +check_upmcrs:
>  	status = ufshcd_get_upmcrs(hba);
>  	if (status != PWR_LOCAL) {
>  		dev_err(hba->dev,
> @@ -4923,11 +4942,14 @@ static irqreturn_t ufshcd_uic_cmd_compl(struct ufs_hba *hba, u32 intr_status)
>  			ufshcd_get_uic_cmd_result(hba);
>  		hba->active_uic_cmd->argument3 =
>  			ufshcd_get_dme_attr_val(hba);
> +		if (!hba->uic_async_done)

Is this check necessary?

> +			hba->active_uic_cmd->cmd_active = 0;
>  		complete(&hba->active_uic_cmd->done);
>  		retval = IRQ_HANDLED;
>  	}
>  
>  	if ((intr_status & UFSHCD_UIC_PWR_MASK) && hba->uic_async_done) {
> +		hba->active_uic_cmd->cmd_active = 0;
>  		complete(hba->uic_async_done);
>  		retval = IRQ_HANDLED;
>  	}
> diff --git a/drivers/scsi/ufs/ufshcd.h b/drivers/scsi/ufs/ufshcd.h
> index 66e5338..be982ed 100644
> --- a/drivers/scsi/ufs/ufshcd.h
> +++ b/drivers/scsi/ufs/ufshcd.h
> @@ -64,6 +64,7 @@ enum dev_cmd_type {
>   * @argument1: UIC command argument 1
>   * @argument2: UIC command argument 2
>   * @argument3: UIC command argument 3
> + * @cmd_active: Indicate if UIC command is outstanding
>   * @done: UIC command completion
>   */
>  struct uic_command {
> @@ -71,6 +72,7 @@ struct uic_command {
>  	u32 argument1;
>  	u32 argument2;
>  	u32 argument3;
> +	int cmd_active;
>  	struct completion done;
>  };
>  



Thanks,
Stanley Chu