Re: [PATCH 4/8] scsi: ufs: Make .get_hba_mac() optional

[Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>]

On Mon, Jun 17, 2024 at 02:07:43PM -0700, Bart Van Assche wrote:
> UFSHCI controllers that are compliant with the UFSHCI 4.0 standard report
> the maximum number of supported commands in the controller capabilities
> register. Use that value if .get_hba_mac == NULL.
> 
> Signed-off-by: Bart Van Assche <bvanassche@acm.org>
> ---
>  drivers/ufs/core/ufs-mcq.c | 12 +++++++-----
>  include/ufs/ufshcd.h       |  4 +++-
>  include/ufs/ufshci.h       |  2 +-
>  3 files changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/ufs/core/ufs-mcq.c b/drivers/ufs/core/ufs-mcq.c
> index 0482c7a1e419..d6f966f4abef 100644
> --- a/drivers/ufs/core/ufs-mcq.c
> +++ b/drivers/ufs/core/ufs-mcq.c
> @@ -138,7 +138,6 @@ EXPORT_SYMBOL_GPL(ufshcd_mcq_queue_cfg_addr);
>   *
>   * MAC - Max. Active Command of the Host Controller (HC)
>   * HC wouldn't send more than this commands to the device.
> - * It is mandatory to implement get_hba_mac() to enable MCQ mode.
>   * Calculates and adjusts the queue depth based on the depth
>   * supported by the HC and ufs device.
>   */
> @@ -146,10 +145,13 @@ int ufshcd_mcq_decide_queue_depth(struct ufs_hba *hba)
>  {
>  	int mac = -EOPNOTSUPP;
>  
> -	if (!hba->vops || !hba->vops->get_hba_mac)
> -		goto err;
> -
> -	mac = hba->vops->get_hba_mac(hba);
> +	if (!hba->vops || !hba->vops->get_hba_mac) {
> +		hba->capabilities =
> +			ufshcd_readl(hba, REG_CONTROLLER_CAPABILITIES);
> +		mac = (hba->capabilities & MASK_TRANSFER_REQUESTS_SLOTS) + 1;
> +	} else {
> +		mac = hba->vops->get_hba_mac(hba);
> +	}
>  	if (mac < 0)
>  		goto err;
>  
> diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
> index d4d63507d090..d32637d267f3 100644
> --- a/include/ufs/ufshcd.h
> +++ b/include/ufs/ufshcd.h
> @@ -325,7 +325,9 @@ struct ufs_pwr_mode_info {
>   * @event_notify: called to notify important events
>   * @reinit_notify: called to notify reinit of UFSHCD during max gear switch
>   * @mcq_config_resource: called to configure MCQ platform resources
> - * @get_hba_mac: called to get vendor specific mac value, mandatory for mcq mode
> + * @get_hba_mac: reports maximum number of outstanding commands supported by
> + *	the controller. Should be implemented for UFSHCI 4.0 or later
> + *	controllers that are not compliant with the UFSHCI 4.0 specification.
>   * @op_runtime_config: called to config Operation and runtime regs Pointers
>   * @get_outstanding_cqs: called to get outstanding completion queues
>   * @config_esi: called to config Event Specific Interrupt
> diff --git a/include/ufs/ufshci.h b/include/ufs/ufshci.h
> index c50f92bf2e1d..899077bba2d2 100644
> --- a/include/ufs/ufshci.h
> +++ b/include/ufs/ufshci.h
> @@ -67,7 +67,7 @@ enum {
>  
>  /* Controller capability masks */
>  enum {
> -	MASK_TRANSFER_REQUESTS_SLOTS		= 0x0000001F,
> +	MASK_TRANSFER_REQUESTS_SLOTS		= 0x000000FF,

This should be a separate fix that comes before this patch. But I believe this
came up during MCQ review as well and I don't remember what was the reply from
Can. 0x1F is the mask for SDB mode and 0xFF is the mask for MCQ mode.

Can, can you comment more?

- Mani

-- 
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