linux-kernel - Re: [PATCH 3/3] media: exynos4-is: fimc-is: replace duplicate pmu node with phandle

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Message-ID: <9c878317-18d6-c483-d182-4c25200ee305@linaro.org>
Date:   Mon, 7 Aug 2023 15:09:40 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Hans Verkuil <hverkuil@...all.nl>,
        Sylwester Nawrocki <s.nawrocki@...sung.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Alim Akhtar <alim.akhtar@...sung.com>,
        linux-media@...r.kernel.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] media: exynos4-is: fimc-is: replace duplicate pmu
 node with phandle

On 07/08/2023 15:06, Hans Verkuil wrote:
> Hi Krzysztof,
> 
> On 22/07/2023 13:54, Krzysztof Kozlowski wrote:
>> Devicetree for the FIMC IS camera included duplicated PMU node as its
>> child like:
>>
>>   soc@0 {
>>     system-controller@...20000 { ... }; // Real PMU
>>
>>     camera@...00000 {
>>       fimc-is@...00000 {
>>         // FIMC IS camera node
>>         pmu@...20000 {
>>           reg = <0x10020000 0x3000>; // Fake PMU node
>>         };
>>       };
>>     };
>>   };
>>
>> This is not a correct representation of the hardware.  Mapping the PMU
>> (Power Management Unit) IO memory should be via syscon-like phandle
>> (samsung,pmu-syscon, already used for other drivers), not by duplicating
>> "pmu" Devicetree node inside the FIMC IS.  Backward compatibility is
>> preserved.
>>
>> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
>> ---
>>  .../platform/samsung/exynos4-is/fimc-is.c     | 33 ++++++++++++++-----
>>  1 file changed, 24 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/media/platform/samsung/exynos4-is/fimc-is.c b/drivers/media/platform/samsung/exynos4-is/fimc-is.c
>> index 530a148fe4d3..c4c191771093 100644
>> --- a/drivers/media/platform/samsung/exynos4-is/fimc-is.c
>> +++ b/drivers/media/platform/samsung/exynos4-is/fimc-is.c
>> @@ -767,12 +767,32 @@ static void fimc_is_debugfs_create(struct fimc_is *is)
>>  static int fimc_is_runtime_resume(struct device *dev);
>>  static int fimc_is_runtime_suspend(struct device *dev);
>>  
>> +static void __iomem *fimc_is_get_pmu_regs(struct device *dev)
>> +{
>> +	struct device_node *node;
>> +	void __iomem *regs;
>> +
>> +	node = of_parse_phandle(dev->of_node, "samsung,pmu-syscon", 0);
>> +	if (!node) {
>> +		dev_warn(dev, "Finding PMU node via deprecated method, update your DTB\n");
>> +		node = of_get_child_by_name(dev->of_node, "pmu");
>> +		if (!node)
>> +			return ERR_PTR(-ENODEV);
>> +	}
>> +
>> +	regs = of_iomap(node, 0);
>> +	of_node_put(node);
>> +	if (!regs)
>> +		return ERR_PTR(-ENOMEM);
> 
> sparse gives me these warnings for these ERR_PTR returns:
> 
> drivers/media/platform/samsung/exynos4-is/fimc-is.c:780:39: warning: incorrect type in return expression (different address spaces)
> drivers/media/platform/samsung/exynos4-is/fimc-is.c:780:39:    expected void [noderef] __iomem *
> drivers/media/platform/samsung/exynos4-is/fimc-is.c:780:39:    got void *

Thanks, indeed. I will use IOMEM_ERR_PTR()

Best regards,
Krzysztof