* Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> [221011 14:30]: > On Tue, Oct 11, 2022 at 05:30:12PM +0300, Tony Lindgren wrote: > > * Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> [221011 13:57]: > > > Hi Sebastian, > > > > > > On Tue, Oct 11, 2022 at 02:37:26PM +0200, Sebastian Reichel wrote: > > > > Hi, > > > > > > > > On Tue, Oct 11, 2022 at 08:45:54AM +0300, Tony Lindgren wrote: > > > > > * Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx> [221004 21:26]: > > > > > > The LCD driver (panel-sony-acx565akm), when probing, starts with line > > > > > > driven low, and then toggles it to high and keeps it there. Also, the > > > > > > line is driven low when powering off the device, and ls released when > > > > > > powering it back on. This means that the reset line should be described > > > > > > as "active low" in DTS. This will be important when the driver is > > > > > > converted to gpiod API which respects the polarity declared in DTS. > > > > > > > > > > We should ensure these patches get merged together with the driver > > > > > change to avoid breaking LCD for booting. Probably no need to have > > > > > the driver quirk handling for inverted polartity in this case. > > > > > > > > > > It's probably easiest to have an immutable branch for the driver > > > > > changes I can base the dts changes on. Or I can ack the dts changes > > > > > if they get merged with the driver. > > > > > > > > Both drivers are already using gpiod API: > > > > > > > > drivers/gpu/drm/panel/panel-sony-acx565akm.c > > > > drivers/gpu/drm/panel/panel-dsi-cm.c > > > > > > I was looking at > > > > > > drivers/video/fbdev/omap2/omapfb/displays/panel-sony-acx565akm.c > > > drivers/video/fbdev/omap2/omapfb/displays/panel-dsi-cm.c > > > > Ah OK that explains :) > > > > > which are not using gpiod. Should they be retired? > > > > Yes we should just get rid of them with omapdrm working just fine. > > Will you be submitting such patches? I'd like to get rid of > of_get_named_gpio() and friends if I can... Adding Tomi to Cc, my guess is he already has such patches and knows better which ones can go :) > > > > So this just breaks things. > > > > > > I missed the drivers in drivers/gpu/... and I see that they essentially > > > abuse gpiod API as gpiod_set_value() operates on logical level > > > (active/inactive) and not absolute (high/low). They should either use > > > the gpiod_*_raw() variants, or they should be adjusted to do the proper > > > thing together with the accompanying DTS change. > > > > > > What are your preferences? > > > > Seems like high/low at the connected device end is what we should use, > > right? Otherwise things will misbehave if the panel is connected to > > some other SoC possibly. > > It is exactly because of this case the driver should use active/inactive > and follow polarity described in DTS. If the driver does: > > gpiod_set_value_cansleep(d->reset, 1); > > then if DTS is saying that the reset line is active low, under the wraps > the line will be driven to "0", but if DTS is saying that the line is > active high, then the very same call will drive the line to "1". > > This allows accommodating different designs without having to change the > driver code. OK Thanks, Tony
