linux-kernel - Re: [PATCH] drm: panel: jd9365da-h3: fix reset signal polarity

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-Id: <20250204124615.4d7a308633a15fc17b2215cb@hugovil.com>
Date: Tue, 4 Feb 2025 12:46:15 -0500
From: Hugo Villeneuve <hugo@...ovil.com>
To: neil.armstrong@...aro.org
Cc: Jagan Teki <jagan@...eble.ai>, Jessica Zhang
 <quic_jesszhan@...cinc.com>, Maarten Lankhorst
 <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>,
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>,
 Simona Vetter <simona@...ll.ch>, Linus Walleij <linus.walleij@...aro.org>,
 Hugo Villeneuve <hvilleneuve@...onoff.com>, stable@...r.kernel.org,
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm: panel: jd9365da-h3: fix reset signal polarity

On Mon, 30 Sep 2024 18:24:44 +0200
neil.armstrong@...aro.org wrote:

> On 30/09/2024 17:05, Hugo Villeneuve wrote:
> > On Mon, 30 Sep 2024 16:38:14 +0200
> > Neil Armstrong <neil.armstrong@...aro.org> wrote:
> > 
> >> Hi,
> >>
> >> On 27/09/2024 15:53, Hugo Villeneuve wrote:
> >>> From: Hugo Villeneuve <hvilleneuve@...onoff.com>
> >>>
> >>> In jadard_prepare() a reset pulse is generated with the following
> >>> statements (delays ommited for clarity):
> >>>
> >>>       gpiod_set_value(jadard->reset, 1); --> Deassert reset
> >>>       gpiod_set_value(jadard->reset, 0); --> Assert reset for 10ms
> >>>       gpiod_set_value(jadard->reset, 1); --> Deassert reset
> >>>
> >>> However, specifying second argument of "0" to gpiod_set_value() means to
> >>> deassert the GPIO, and "1" means to assert it. If the reset signal is
> >>> defined as GPIO_ACTIVE_LOW in the DTS, the above statements will
> >>> incorrectly generate the reset pulse (inverted) and leave it asserted
> >>> (LOW) at the end of jadard_prepare().
> >>
> >> Did you check the polarity in DTS of _all_ users of this driver ?
> > 
> > Hi Neil,
> > I confirmed that no in-tree DTS is referencing this driver. I did a
> > search of all the compatible strings defined in the
> > "jadard,jd9365da-h3.yaml" file. I also did the same on Debian code
> > search.
> 
> 
> OK then:
> Reviewed-by: Neil Armstrong <neil.armstrong@...aro.org>

Hi Neil,
it seems this patch was never applied/picked-up?

Hugo.


> 
> > 
> > Hugo.
> > 
> > 
> >>
> >> Neil
> >>
> >>>
> >>> Fix reset behavior by inverting gpiod_set_value() second argument
> >>> in jadard_prepare(). Also modify second argument to devm_gpiod_get()
> >>> in jadard_dsi_probe() to assert the reset when probing.
> >>>
> >>> Do not modify it in jadard_unprepare() as it is already properly
> >>> asserted with "1", which seems to be the intended behavior.
> >>>
> >>> Fixes: 6b818c533dd8 ("drm: panel: Add Jadard JD9365DA-H3 DSI panel")
> >>> Cc: <stable@...r.kernel.org>
> >>> Signed-off-by: Hugo Villeneuve <hvilleneuve@...onoff.com>
> >>> ---
> >>>    drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c | 8 ++++----
> >>>    1 file changed, 4 insertions(+), 4 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> >>> index 44897e5218a69..6fec99cf4d935 100644
> >>> --- a/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> >>> +++ b/drivers/gpu/drm/panel/panel-jadard-jd9365da-h3.c
> >>> @@ -110,13 +110,13 @@ static int jadard_prepare(struct drm_panel *panel)
> >>>    	if (jadard->desc->lp11_to_reset_delay_ms)
> >>>    		msleep(jadard->desc->lp11_to_reset_delay_ms);
> >>>    
> >>> -	gpiod_set_value(jadard->reset, 1);
> >>> +	gpiod_set_value(jadard->reset, 0);
> >>>    	msleep(5);
> >>>    
> >>> -	gpiod_set_value(jadard->reset, 0);
> >>> +	gpiod_set_value(jadard->reset, 1);
> >>>    	msleep(10);
> >>>    
> >>> -	gpiod_set_value(jadard->reset, 1);
> >>> +	gpiod_set_value(jadard->reset, 0);
> >>>    	msleep(130);
> >>>    
> >>>    	ret = jadard->desc->init(jadard);
> >>> @@ -1131,7 +1131,7 @@ static int jadard_dsi_probe(struct mipi_dsi_device *dsi)
> >>>    	dsi->format = desc->format;
> >>>    	dsi->lanes = desc->lanes;
> >>>    
> >>> -	jadard->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_LOW);
> >>> +	jadard->reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
> >>>    	if (IS_ERR(jadard->reset)) {
> >>>    		DRM_DEV_ERROR(&dsi->dev, "failed to get our reset GPIO\n");
> >>>    		return PTR_ERR(jadard->reset);
> >>>
> >>> base-commit: 18ba6034468e7949a9e2c2cf28e2e123b4fe7a50
> >>
> >>
> > 
> > 
> 
> 


-- 
Hugo Villeneuve