From: "Alex G." <mr.nuke.me@gmail.com>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: dri-devel@lists.freedesktop.org, devicetree@vger.kernel.org,
Jernej Skrabec <jernej.skrabec@siol.net>,
Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
Neil Armstrong <narmstrong@baylibre.com>,
David Airlie <airlied@linux.ie>, Mark Brown <broonie@kernel.org>,
Jonas Karlman <jonas@kwiboo.se>,
linux-kernel@vger.kernel.org, Andrzej Hajda <a.hajda@samsung.com>,
Rob Herring <robh+dt@kernel.org>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCH 1/2] drm/bridge: sii902x: Enable I/O and core VCC supplies if present
Date: Mon, 28 Sep 2020 12:35:01 -0500 [thread overview]
Message-ID: <9c3ce766-743c-705f-7926-21e753c2d02d@gmail.com> (raw)
In-Reply-To: <20200926184919.GB98875@ravnborg.org>
On 9/26/20 1:49 PM, Sam Ravnborg wrote:
> Hi Alexandru
>
> On Thu, Sep 24, 2020 at 03:05:05PM -0500, Alexandru Gagniuc wrote:
>> On the SII9022, the IOVCC and CVCC12 supplies must reach the correct
>> voltage before the reset sequence is initiated. On most boards, this
>> assumption is true at boot-up, so initialization succeeds.
>>
>> However, when we try to initialize the chip with incorrect supply
>> voltages, it will not respond to I2C requests. sii902x_probe() fails
>> with -ENXIO.
>>
>> To resolve this, look for the "iovcc" and "cvcc12" regulators, and
>> make sure they are enabled before starting the reset sequence. If
>> these supplies are not available in devicetree, then they will default
>> to dummy-regulator. In that case everything will work like before.
>>
>> This was observed on a STM32MP157C-DK2 booting in u-boot falcon mode.
>> On this board, the supplies would be set by the second stage
>> bootloader, which does not run in falcon mode.
>>
>> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
>
> One nitpick here. The binding should be present in the tree before
> you start using it. So this patch should be applied after the binding.
It is :)
* arch/arm/boot/dts/stm32mp15xx-dkx.dtsi
Alex
> One detail below - I think others have already commented on the rest.
[snip]
WARNING: multiple messages have this Message-ID (diff)
From: "Alex G." <mr.nuke.me@gmail.com>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: devicetree@vger.kernel.org,
Jernej Skrabec <jernej.skrabec@siol.net>,
Thomas Bogendoerfer <tsbogend@alpha.franken.de>,
Rob Herring <robh+dt@kernel.org>,
Neil Armstrong <narmstrong@baylibre.com>,
Mauro Carvalho Chehab <mchehab+huawei@kernel.org>,
Jonas Karlman <jonas@kwiboo.se>,
linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org,
Andrzej Hajda <a.hajda@samsung.com>,
David Airlie <airlied@linux.ie>, Mark Brown <broonie@kernel.org>,
Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Subject: Re: [PATCH 1/2] drm/bridge: sii902x: Enable I/O and core VCC supplies if present
Date: Mon, 28 Sep 2020 12:35:01 -0500 [thread overview]
Message-ID: <9c3ce766-743c-705f-7926-21e753c2d02d@gmail.com> (raw)
In-Reply-To: <20200926184919.GB98875@ravnborg.org>
On 9/26/20 1:49 PM, Sam Ravnborg wrote:
> Hi Alexandru
>
> On Thu, Sep 24, 2020 at 03:05:05PM -0500, Alexandru Gagniuc wrote:
>> On the SII9022, the IOVCC and CVCC12 supplies must reach the correct
>> voltage before the reset sequence is initiated. On most boards, this
>> assumption is true at boot-up, so initialization succeeds.
>>
>> However, when we try to initialize the chip with incorrect supply
>> voltages, it will not respond to I2C requests. sii902x_probe() fails
>> with -ENXIO.
>>
>> To resolve this, look for the "iovcc" and "cvcc12" regulators, and
>> make sure they are enabled before starting the reset sequence. If
>> these supplies are not available in devicetree, then they will default
>> to dummy-regulator. In that case everything will work like before.
>>
>> This was observed on a STM32MP157C-DK2 booting in u-boot falcon mode.
>> On this board, the supplies would be set by the second stage
>> bootloader, which does not run in falcon mode.
>>
>> Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
>
> One nitpick here. The binding should be present in the tree before
> you start using it. So this patch should be applied after the binding.
It is :)
* arch/arm/boot/dts/stm32mp15xx-dkx.dtsi
Alex
> One detail below - I think others have already commented on the rest.
[snip]
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next prev parent reply other threads:[~2020-09-28 17:35 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-24 20:05 [PATCH 1/2] drm/bridge: sii902x: Enable I/O and core VCC supplies if present Alexandru Gagniuc
2020-09-24 20:05 ` Alexandru Gagniuc
2020-09-24 20:05 ` [PATCH 2/2] dt-bindings: display: sii902x: Add supply bindings Alexandru Gagniuc
2020-09-24 20:05 ` Alexandru Gagniuc
2020-09-26 18:42 ` Sam Ravnborg
2020-09-26 18:42 ` Sam Ravnborg
2020-09-24 20:22 ` [PATCH 1/2] drm/bridge: sii902x: Enable I/O and core VCC supplies if present Fabio Estevam
2020-09-24 20:22 ` Fabio Estevam
2020-09-24 20:34 ` Alex G.
2020-09-24 20:34 ` Alex G.
2020-09-26 12:50 ` Dan Carpenter
2020-09-26 12:50 ` Dan Carpenter
2020-09-26 12:50 ` Dan Carpenter
2020-09-26 12:50 ` Dan Carpenter
2020-09-26 18:49 ` Sam Ravnborg
2020-09-26 18:49 ` Sam Ravnborg
2020-09-28 17:35 ` Alex G. [this message]
2020-09-28 17:35 ` Alex G.
2020-09-28 19:03 ` Sam Ravnborg
2020-09-28 19:03 ` Sam Ravnborg
2020-09-28 17:30 ` [PATCH v2 " Alexandru Gagniuc
2020-09-28 17:30 ` Alexandru Gagniuc
2020-09-28 17:30 ` [PATCH v2 2/2] dt-bindings: display: sii902x: Add supply bindings Alexandru Gagniuc
2020-09-28 17:30 ` Alexandru Gagniuc
2020-09-29 20:17 ` Rob Herring
2020-09-29 20:17 ` Rob Herring
2020-10-20 1:24 ` [PATCH v2 1/2] drm/bridge: sii902x: Enable I/O and core VCC supplies if present Alex G.
2020-10-20 1:24 ` Alex G.
2020-10-20 7:16 ` Sam Ravnborg
2020-10-20 7:16 ` Sam Ravnborg
2020-10-20 14:01 ` Alex G.
2020-10-20 14:01 ` Alex G.
2020-10-20 15:08 ` Sam Ravnborg
2020-10-20 15:08 ` Sam Ravnborg
2020-10-20 22:14 ` [PATCH v3 1/3] drm/bridge: sii902x: Refactor init code into separate function Alexandru Gagniuc
2020-10-20 22:14 ` Alexandru Gagniuc
2020-10-20 22:14 ` [PATCH v3 2/3] drm/bridge: sii902x: Enable I/O and core VCC supplies if present Alexandru Gagniuc
2020-10-20 22:14 ` Alexandru Gagniuc
2020-11-08 10:55 ` Sam Ravnborg
2020-11-08 10:55 ` Sam Ravnborg
2020-10-20 22:14 ` [PATCH v3 3/3] dt-bindings: display: sii902x: Add supply bindings Alexandru Gagniuc
2020-10-20 22:14 ` Alexandru Gagniuc
2020-09-26 0:13 [PATCH 1/2] drm/bridge: sii902x: Enable I/O and core VCC supplies if present kernel test robot
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