Re: [RFC PATCH v1] ufs: poll HCS.UCRDY before issuing a UIC command

[Adrian Hunter <adrian.hunter@intel.com>]

On 9/05/23 11:24, Kiwoong Kim wrote:
> With auto hibern8 enabled, UIC could be working
> for a while to process a hibern8 operation and HCI
> reports UIC not ready for a short term through HCS.UCRDY.
> And UFS driver can't recognize the operation.
> UFSHCI spec specifies UCRDY like this:
> whether the host controller is ready to process UIC COMMAND
> 
> The 'ready' could be seen as many different meanings. If the meaning
> includes not processing any request from HCI, processing a hibern8
> operation can be 'not ready'. In this situation, the driver needs to
> wait until the operations is completed.
> 
> Signed-off-by: Kiwoong Kim <kwmad.kim@samsung.com>
> ---
>  drivers/ufs/core/ufshcd.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/ufs/core/ufshcd.c b/drivers/ufs/core/ufshcd.c
> index 96ce6af..fc79539 100644
> --- a/drivers/ufs/core/ufshcd.c
> +++ b/drivers/ufs/core/ufshcd.c
> @@ -2368,7 +2368,18 @@ static inline int ufshcd_hba_capabilities(struct ufs_hba *hba)
>   */
>  static inline bool ufshcd_ready_for_uic_cmd(struct ufs_hba *hba)
>  {
> -	return ufshcd_readl(hba, REG_CONTROLLER_STATUS) & UIC_COMMAND_READY;
> +	ktime_t timeout = ktime_add_ms(ktime_get(), UIC_CMD_TIMEOUT);
> +	u32 val = 0;
> +
> +	do {
> +		val = ufshcd_readl(hba, REG_CONTROLLER_STATUS) &
> +			UIC_COMMAND_READY;
> +		if (val)
> +			break;
> +		usleep_range(500, 1000);

Pedantically, the sleep probably needs to be less than the
auto-hibernate idle timer period?

> +	} while (ktime_before(ktime_get(), timeout));

read_poll_timeout() would be a better choice for I/O polling

> +
> +	return val ? true : false;
>  }
>  
>  /**