Re: [PATCH 2/2] scsi: ufs: core: Fix the code for entering hibernation

[Bart Van Assche <bvanassche@acm.org>]

On 8/22/24 4:34 PM, Bao D. Nguyen wrote:
> Let's say you are sending a ufshcd_uic_pwr_ctrl() command. You will get 
> 2 uic completion interrupts:
> [1] ufshcd_uic_cmd_compl() is called for the first interrupt which 
> happens to be UFSHCD_UIC_PWR_MASK only. At the end of the 
> ufshcd_uic_pwr_ctrl(), you would set the hba->active_uic_cmd to NULL.

That's not correct. ufshcd_uic_pwr_ctrl() only clears
hba->active_uic_cmd after the power mode change interrupt has been
processed.

> [2]The second uic completion interrupt for UIC_COMMAND_COMP is delayed.
> This interrupt is newly introduced by this patch.

If UIC_COMMAND_COMPL is delivered after UFSHCD_UIC_PWR_MASK then the
UIC_COMMAND_COMPL interrupt will be ignored because hba->active_uic_cmd
is cleared by ufshcd_uic_pwr_ctrl() after it has processed the
power mode change interrupt.

> Now let's say you have a new UIC command coming via 
> ufshcd_send_uic_cmd(). The ufshcd_dispatch_uic_cmd() will update your 
> hba->active_uic_cmd to the new uic_cmd.

UIC command processing is serialized by hba->uic_cmd_mutex. Hence only
one UIC command is processed at any given time.

Does this address your concerns?

Thanks,

Bart.