Re: [PATCH v1 2/2] scsi: ufs: core: Reduce the sleep before vcc can be powered on

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

On 10/7/25 12:04 AM, Peter Wang (王信友) wrote:
> On Fri, 2025-10-03 at 14:27 -0700, Bao D. Nguyen wrote:
>> With the current or recent offerings of ufs devices in the market, 
>> the requirement is 1ms. For example, the Kioxia datasheet says
>> "Vcc shall be kept less than 0.3V for at least 1ms before it goes
>> beyond 0.3V again". Similarly other vendors have this 1ms
>> requirement. So I believe this indicates the worst case scenario. 
>> I understand there may be very old devices that are upgrading the 
>> kernel only. In that case I don't know the specifics for these old
>> ufs parts as mentioned.
> 
> Hi Bao,
> 
> Please consider using module_param_cb to set the default
> delay to 2ms(or 1ms). At the same time, we should keep the
> flexibility for devices that may require a longer delay by
> allowing them to extend the delay through a module parameter.

Why a kernel module parameter? Why can't the default delay be set by
ufshcd_variant_ops.init()?

Thanks,

Bart.