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

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Message-Id: <5A763511-72C8-4CDE-AF1F-8F1A04390BAE@goldelico.com>
Date:   Tue, 28 Sep 2021 13:50:13 +0200
From:   "H. Nikolaus Schaller" <hns@...delico.com>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Kees Cook <keescook@...omium.org>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Andrzej Hajda <a.hajda@...sung.com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Robert Foss <robert.foss@...aro.org>,
        Laurent Pinchart <Laurent.pinchart@...asonboard.com>,
        Jernej Skrabec <jernej.skrabec@...il.com>,
        Ezequiel Garcia <ezequiel@...labora.com>,
        Harry Wentland <harry.wentland@....com>,
        Sam Ravnborg <sam@...nborg.org>,
        Maxime Ripard <maxime@...no.tech>,
        Hans Verkuil <hverkuil-cisco@...all.nl>,
        Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        Paul Boddie <paul@...die.org.uk>, devicetree@...r.kernel.org,
        linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        letux-kernel@...nphoenux.org, Jonas Karlman <jonas@...boo.se>,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH v4 10/10] drm/ingenic: add some jz4780 specific features



> Am 28.09.2021 um 12:06 schrieb H. Nikolaus Schaller <hns@...delico.com>:
> 
>>> 
>>> +
>>> +	/* RGB output control may be superfluous. */
>>> +	if (soc_info->has_rgbc)
>>> +		regmap_write(priv->map, JZ_REG_LCD_RGBC,
>>> +			     JZ_LCD_RGBC_RGB_FORMAT_ENABLE |
>>> +			     JZ_LCD_RGBC_ODD_RGB |
>>> +			     JZ_LCD_RGBC_EVEN_RGB);
>> 
>> 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@...ux:~# devmem2 0x13050090
/dev/mem opened.
Memory mapped at address 0x77e14000.
Value at address 0x13050090 (0x77e14090): 0x0
root@...ux:~# devmem2 0x13050090 w 0x80
/dev/mem opened.
Memory mapped at address 0x77e38000.
Value at address 0x13050090 (0x77e38090): 0x0
Written 0x80; readback 0x80
root@...ux:~# 

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,
Nikolaus