Re: [PATCH 1/1] scsi: ufs: Generalize UFS Interconnect Layer (UIC) command support

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On 5/2/2013 12:49 PM, Santosh Y wrote:
-static inline void
-ufshcd_send_uic_command(struct ufs_hba *hba, struct uic_command *uic_cmnd)
+static int ufshcd_send_uic_command(struct ufs_hba *hba,
+               struct uic_command *uic_cmnd, int retries)
  {
+       int err = 0;
+       unsigned long flags;
+
+       if (unlikely(mutex_trylock(&hba->uic_cmd_mutex))) {
+               mutex_unlock(&hba->uic_cmd_mutex);
+               dev_err(hba->dev, "%s: called without prepare command\n",
+                               __func__);
+               BUG();
+       }
+
+retry:
+       /* check if controller is ready to accept UIC commands */
+       if (!(readl(hba->mmio_base + REG_CONTROLLER_STATUS) &
+                               UIC_COMMAND_READY)) {
+               dev_err(hba->dev, "Controller not ready to accept UIC commands\n");
+               err = -EIO;
+               goto out;
+       }
+
+       init_completion(&uic_cmnd->completion);
+
+       spin_lock_irqsave(hba->host->host_lock, flags);
+
+       /* enable UIC related interrupts */
+       if (!(hba->int_enable_mask & UIC_COMMAND_COMPL)) {
+               hba->int_enable_mask |= UIC_COMMAND_COMPL;
+               ufshcd_int_config(hba, UFSHCD_INT_ENABLE);
+       }
+

No need to check if the interrupt is already enabled, it can be
directly enabled.

That would be unnecessary device access (writel) every time we send a UIC command.



         /* Write Args */
         writel(uic_cmnd->argument1,
               (hba->mmio_base + REG_UIC_COMMAND_ARG_1));
@@ -415,6 +491,45 @@ ufshcd_send_uic_command(struct ufs_hba *hba, struct uic_command *uic_cmnd)
         /* Write UIC Cmd */
         writel((uic_cmnd->command & COMMAND_OPCODE_MASK),
                (hba->mmio_base + REG_UIC_COMMAND));
+
+       /* flush to make sure h/w sees the write */
+       readl(hba->mmio_base + REG_UIC_COMMAND);
+
+       spin_unlock_irqrestore(hba->host->host_lock, flags);
+

mutex lock/unlock can be done in the send_uic_command, It will
simplify the process for the caller.

 ufshcd_dme_get_attr()
 {
   1) ufshcd_prepare_uic_command_lck();
   2) ufshcd_send_uic_command();
   3) Read arg3 to know the value of Uni-pro attribute.
   4) ufshcd_unprepare_uic_command_unlck();
 }

Step 3 above is optional for some of the UIC commands but when it is required it should be done with mutex lock held as the hba->active_uic_cmd might be modified by some one else before value present hba->active_uic_cmd->argument3 is read.

But thinking more on this holding lock only in send_uic_command() is feasible.


+       err = wait_for_completion_timeout(
+                       &uic_cmnd->completion, UIC_COMMAND_TIMEOUT);
+       if (!err) {
+               err = -ETIMEDOUT;
+       } else if (uic_cmnd->argument2 & MASK_UIC_COMMAND_RESULT) {
+               /* something bad with h/w or arguments, try again */
+               if (--retries)
+                       goto retry;
+


--
Regards,
Sujit
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