Re: [PATCH v5 07/13] drm/bridge: cdns-dsi: Wait for Clk and Data Lanes to be ready

[Aradhya Bhatia <aradhya.bhatia@linux.dev>]

On 22/10/24 11:55, Devarsh Thakkar wrote:
> Hi Aradhya,
> 
> Thanks for the patch.
> 
> On 20/10/24 01:24, Aradhya Bhatia wrote:
>> From: Aradhya Bhatia <a-bhatia1@ti.com>
> 
> [...]
> 
>> +	/*
>> +	 * Now that the DSI Link and DSI Phy are initialized,
>> +	 * wait for the CLK and Data Lanes to be ready.
>> +	 */
>> +	tmp = CLK_LANE_RDY;
>> +	for (int i = 0; i < nlanes; i++)
>> +		tmp |= DATA_LANE_RDY(i);
>> +
>> +	if (readl_poll_timeout(dsi->regs + MCTL_MAIN_STS, status,
>> +			       status & tmp, 100, 500000))
> 
> The above would mark the condition as true even if one data lane gets ready. I
> think we need to poll until all data lanes are marked as ready. Also good to
> give a warning in case we time out.
> 
> IMHO below should fix this:
>         WARN_ON_ONCE(readl_poll_timeout(dsi->regs + MCTL_MAIN_STS, status,
>                                        (tmp == (status & tmp)), 100, 0));
> 

That's how the condition should be, yes! Thanks for the catch!

I would still prefer to keep dev_err instead of WARN_ON_ONCE, because
the latter stack-dumps during boot once, and then can never be seen
again during multiple modesets. The noise in the dmesg is not worth
the issue either.

With dev_err, it can show a clear print once every time it times out.

-- 
Regards
Aradhya