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

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

On 8/21/24 6:05 PM, Bao D. Nguyen wrote:
> If I understand correctly, the link is hibernated because we had a 
> successful ufshcd_uic_hibern8_enter() earlier. Then the 
> ufshcd_uic_pwr_ctrl() is invoked probably from a power mode change 
> command? (a callstack would be helpful in this case).

Hi Bao,

ufshcd_uic_hibern8_enter() calls ufshcd_uic_pwr_ctrl() directly. The
former function causes the latter to send the UIC_CMD_DME_HIBER_ENTER
command. Although UIC_CMD_DME_HIBER_ENTER causes the link to enter the
hibernation state, the code in ufshcd_uic_pwr_ctrl() for re-enabling
interrupts causes the UFS host controller that I'm testing to exit the
hibernation state.

> Anyway, accessing the UFSHCI host controller registers space somehow 
> affected the M-PHY link state? If my understanding is correct, it seems 
> like a hardware issue that we are trying to work around?

Yes, this is a workaround particular behavior of a particular UFS
controller.

Thanks,

Bart.