linux-kernel - Re: [PATCH v2] Revert v6.2-rc1 and later "ARM: dts: bcm2835-rpi: Use firmware clocks for display"

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Message-Id: <D6C59720-57A3-4EE0-A78C-F259F8906C0D@goldelico.com>
Date: Thu, 23 Jan 2025 15:05:53 +0100
From: "H. Nikolaus Schaller" <hns@...delico.com>
To: Florian Fainelli <florian.fainelli@...adcom.com>,
 Stefan Wahren <wahrenst@....net>
Cc: Rob Herring <robh+dt@...nel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
 Florian Fainelli <f.fainelli@...il.com>,
 Ray Jui <rjui@...adcom.com>,
 Scott Branden <sbranden@...adcom.com>,
 devicetree <devicetree@...r.kernel.org>,
 Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
 stable <stable@...r.kernel.org>,
 Broadcom internal kernel review list <bcm-kernel-feedback-list@...adcom.com>,
 linux-rpi-kernel@...ts.infradead.org,
 arm-soc <linux-arm-kernel@...ts.infradead.org>,
 Discussions about the Letux Kernel <letux-kernel@...nphoenux.org>
Subject: Re: [PATCH v2] Revert v6.2-rc1 and later "ARM: dts: bcm2835-rpi: Use
 firmware clocks for display"

Hi,

> Am 20.01.2025 um 17:34 schrieb Florian Fainelli <florian.fainelli@...adcom.com>:
> 
> 
> 
> On 1/19/2025 7:04 AM, 'H. Nikolaus Schaller' via BCM-KERNEL-FEEDBACK-LIST,PDL wrote:
>> Hi Stefan,
>>> Am 19.01.2025 um 01:36 schrieb Stefan Wahren <wahrenst@....net>:
>>> 
>>> Hi,
>>> 
>>> Am 18.01.25 um 17:27 schrieb H. Nikolaus Schaller:
>>>> This reverts commit 27ab05e1b7e5c5ec9b4f658e1b2464c0908298a6.
>>>> 
>>>> I tried to upgrade a RasPi 3B+ with Waveshare 7inch HDMI LCD
>>>> from 6.1.y to 6.6.y but found that the display is broken with
>>>> this log message:
>>>> 
>>>> [   17.776315] vc4-drm soc:gpu: bound 3f400000.hvs (ops vc4_drm_unregister [vc4])
>>>> [   17.784034] platform 3f806000.vec: deferred probe pending
>>>> 
>>>> Some tests revealed that while 6.1.y works, 6.2-rc1 is already broken but all
>>>> newer kernels as well. And a bisect did lead me to this patch.
>>> I successfully tested every Kernel release until Linux 6.13-rc with the
>>> Raspberry Pi 3B+, so i prefer to step back and analyze this issue further.
>> Yes, I would be happy with any solution.
>>> What kernel config do you use ?
>> a private one which enables application specific drivers.
>>> What is the value of CONFIG_CLK_RASPBERRYPI ?
>> CONFIG_CLK_RASPBERRYPI is not set
>> I checked where this is defined and it is in bcm2835_defconfig and
>> multi_v7_defconfig by
>> 4c6f5d4038af2c ("ARM: defconfig: enable cpufreq driver for RPi")
>> which hides this requirement quite well and got therefore unnoticed...
>> Setting CONFIG_CLK_RASPBERRYPI=y makes HDMI work without my proposed revert.
>> Tested with v6.2.16, v6.6.72, v6.12.10 and v6.13-rc7.
> 
> I have been burned before by something similar and came up with this patch series that I should resubmit after addressing Conor's comment:
> 
> https://lore.kernel.org/all/20240513235234.1474619-1-florian.fainelli@broadcom.com/
> 
> Essentially, it removes the guess work, all you have to do is enable CONFIG_ARCH_BCM2835 and it just works, which is how it should be IMHO.

Sounds like a good idea!

Supported-by: H. Nikolaus Schaller <hns@...delico.com>

BR,
Nikoalus