[Intel-gfx] [PATCH] drm/i915/dsi: fix VBT send packet port selection for dual link DSI

[Jani Nikula]

On Mon, 28 Nov 2022, Jani Nikula <jani.nikula at linux.intel.com> wrote:
> On Sat, 26 Nov 2022, Mikko Kovanen <mikko.kovanen at aavamobile.com> wrote:
>> intel_dsi->ports contains bitmask of enabled ports and correspondingly
>> logic for selecting port for VBT packet sending must use port specific
>> bitmask when deciding appropriate port.
>>
>> Fixes: 08c59dde71b7 ("drm/i915/dsi: fix VBT send packet port selection for ICL+")
>> Cc: stable at vger.kernel.org
>> Signed-off-by: Mikko Kovanen <mikko.kovanen at aavamobile.com>
>
> Holy crap, that's embarrassing! Thanks!
>
> Despite the mistake, it always works for single-link DSI as well as port
> A on dual-link DSI, which probably covers most use cases. It's the
> commands targeted at port B (VLV+ DSI) or port C (ICL+ DSI) that go
> haywire.
>
> Reviewed-by: Jani Nikula <jani.nikula at intel.com>

Pushed to drm-intel-next, thanks for the patch.

And promptly after pushing I realized I failed to added the link to the
issue in the commit message. Here it is for posterity:

Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/7601


BR,
Jani.

>
>> ---
>>  drivers/gpu/drm/i915/display/intel_dsi_vbt.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/display/intel_dsi_vbt.c b/drivers/gpu/drm/i915/display/intel_dsi_vbt.c
>> index 75e8cc4337c9..fce69fa446d5 100644
>> --- a/drivers/gpu/drm/i915/display/intel_dsi_vbt.c
>> +++ b/drivers/gpu/drm/i915/display/intel_dsi_vbt.c
>> @@ -137,9 +137,9 @@ static enum port intel_dsi_seq_port_to_port(struct intel_dsi *intel_dsi,
>>  		return ffs(intel_dsi->ports) - 1;
>>  
>>  	if (seq_port) {
>> -		if (intel_dsi->ports & PORT_B)
>> +		if (intel_dsi->ports & BIT(PORT_B))
>>  			return PORT_B;
>> -		else if (intel_dsi->ports & PORT_C)
>> +		else if (intel_dsi->ports & BIT(PORT_C))
>>  			return PORT_C;
>>  	}

-- 
Jani Nikula, Intel Open Source Graphics Center