Re: [PATCH 05/11] drm/bridge: analogix-anx78xx: correct value of TX_P0

From: Brian Masney <masneyb@onstation.org>
To: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Cc: Andrzej Hajda <a.hajda@samsung.com>,
	bjorn.andersson@linaro.org, robh+dt@kernel.org,
	agross@kernel.org, narmstrong@baylibre.com, robdclark@gmail.com,
	sean@poorly.run, airlied@linux.ie, daniel@ffwll.ch,
	mark.rutland@arm.com, Laurent.pinchart@ideasonboard.com,
	jonas@kwiboo.se, jernej.skrabec@siol.net,
	linus.walleij@linaro.org, dri-devel@lists.freedesktop.org,
	devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-arm-msm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	freedreno@lists.freedesktop.org
Subject: Re: [PATCH 05/11] drm/bridge: analogix-anx78xx: correct value of TX_P0
Date: Mon, 16 Sep 2019 06:40:04 -0400	[thread overview]
Message-ID: <20190916104004.GB1644@onstation.org> (raw)
In-Reply-To: <98199a9b-f7e0-ef95-62d7-401273457692@collabora.com>

On Mon, Sep 16, 2019 at 12:36:19PM +0200, Enric Balletbo i Serra wrote:
> Hi Andrzej and Brian
> 
> On 16/9/19 12:02, Andrzej Hajda wrote:
> > On 15.08.2019 02:48, Brian Masney wrote:
> >> When attempting to configure this driver on a Nexus 5 phone (msm8974),
> >> setting up the dummy i2c bus for TX_P0 would fail due to an -EBUSY
> >> error. The downstream MSM kernel sources [1] shows that the proper value
> >> for TX_P0 is 0x78, not 0x70, so correct the value to allow device
> >> probing to succeed.
> >>
> >> [1] https://github.com/AICP/kernel_lge_hammerhead/blob/n7.1/drivers/video/slimport/slimport_tx_reg.h
> >>
> >> Signed-off-by: Brian Masney <masneyb@onstation.org>
> >> ---
> >>  drivers/gpu/drm/bridge/analogix-anx78xx.h | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpu/drm/bridge/analogix-anx78xx.h b/drivers/gpu/drm/bridge/analogix-anx78xx.h
> >> index 25e063bcecbc..bc511fc605c9 100644
> >> --- a/drivers/gpu/drm/bridge/analogix-anx78xx.h
> >> +++ b/drivers/gpu/drm/bridge/analogix-anx78xx.h
> >> @@ -6,7 +6,7 @@
> >>  #ifndef __ANX78xx_H
> >>  #define __ANX78xx_H
> >>  
> >> -#define TX_P0				0x70
> >> +#define TX_P0				0x78
> > 
> > 
> > This bothers me little. There are no upstream users, grepping android
> > sources suggests that both values can be used [1][2]  (grep for "#define
> > TX_P0"), moreover there is code suggesting both values can be valid [3].
> > 
> > Could you verify datasheet which i2c slave addresses are valid for this
> > chip, if both I guess this patch should be reworked.
> > 
> 
> On my case the valid i2c slave address is 0x70 (from datasheet, very sorry I
> can't share it) and the bridge used is an ANX7814, it could be that ANX7808 or
> ANX7812 have different slave addresses?

I haven't been able to find any of the datasheets for these devices
online. Product briefs are online (such as 
https://www.analogix.com/en/system/files/ANX7808_product_brief.pdf), but
they don't provide this type of information.

Brian