[PATCH v2 1/4] drm/dp: Add helper to set LTTPRs in transparent mode

[Jani Nikula]

On Wed, 11 Dec 2024, Dmitry Baryshkov <dmitry.baryshkov at linaro.org> wrote:
> On Wed, Dec 11, 2024 at 03:42:27PM +0100, Johan Hovold wrote:
>> On Wed, Dec 11, 2024 at 03:04:12PM +0200, Abel Vesa wrote:
>>  
>> > +/**
>> > + * drm_dp_lttpr_set_transparent_mode - set the LTTPR in transparent mode
>> > + * @aux: DisplayPort AUX channel
>> > + * @enable: Enable or disable transparent mode
>> > + *
>> > + * Returns 0 on success or a negative error code on failure.
>> > + */
>> > +int drm_dp_lttpr_set_transparent_mode(struct drm_dp_aux *aux, bool enable)
>> > +{
>> > +	u8 val = enable ? DP_PHY_REPEATER_MODE_TRANSPARENT :
>> > +			  DP_PHY_REPEATER_MODE_NON_TRANSPARENT;
>> > +	int ret = drm_dp_dpcd_writeb(aux, DP_PHY_REPEATER_MODE, val);
>> > +
>> > +	return ret == 1 ? 0 : ret;
>> 
>> This looks correct, but I had to go look at drm_dp_dpcd_writeb() to make
>> sure it never returns 0 (for short transfers).
>> 
>> > +}
>> > +EXPORT_SYMBOL(drm_dp_lttpr_set_transparent_mode);
>> 
>> This appears to be what the driver currently uses, but why not
>> EXPORT_SYMBOL_GPL?
>
> $ git grep EXPORT_SYMBOL drivers/gpu/drm/*.c | wc -l
> 962
> $ git grep EXPORT_SYMBOL_GPL drivers/gpu/drm/*.c | wc -l
> 93

It's even more tilted under display/.

BR,
Jani.


-- 
Jani Nikula, Intel