Re: [PATCH v4 10/10] drm/ingenic: add some jz4780 specific features

From: H. Nikolaus Schaller
Date: Tue Sep 28 2021 - 07:51:04 EST

> Am 28.09.2021 um 12:06 schrieb H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>:
>>> +
>>> + /* RGB output control may be superfluous. */
>>> + if (soc_info->has_rgbc)
>>> + regmap_write(priv->map, JZ_REG_LCD_RGBC,
>> ingenic-drm only supports RGB output right now, so I guess the RGB_FORMAT_ENABLE bit needs to be set in patch [2/10], otherwise patch [2/10] cannot state that it adds support for the JZ4780, if it doesn't actually work.

interestingly it works without setting anything in this register.

>> The other two bits can be dropped, they are already set in ingenic_drm_encoder_atomic_mode_set().
> Ok.

Setting it manually doesn't change anything visible:

root@letux:~# devmem2 0x13050090
/dev/mem opened.
Memory mapped at address 0x77e14000.
Value at address 0x13050090 (0x77e14090): 0x0
root@letux:~# devmem2 0x13050090 w 0x80
/dev/mem opened.
Memory mapped at address 0x77e38000.
Value at address 0x13050090 (0x77e38090): 0x0
Written 0x80; readback 0x80

Same for 0x130A0090. Maybe this lcdc register
is not used at all - at least for HDMI?

So I'd suggest to drop this whole patch from v5.

BR and thanks,