Re: [PATCH] driver: have dev_platform_ioremap_resource return error pointer

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

Hello Sascha,

On 4/14/25 11:07, Sascha Hauer wrote:
> On Mon, Apr 14, 2025 at 08:23:03AM +0200, Ahmad Fatoum wrote:
>> From: Ahmad Fatoum <a.fatoum@barebox.org>
>>
>> devm_request_mem_region doesn't return NULL on error on Linux and thus
>> it should neither in barebox. Fix this.
>>
>> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>> ---
>>  drivers/base/driver.c  | 2 ++
>>  include/linux/device.h | 2 +-
>>  2 files changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/base/driver.c b/drivers/base/driver.c
>> index edba037fa2dd..4e361a96c9ee 100644
>> --- a/drivers/base/driver.c
>> +++ b/drivers/base/driver.c
>> @@ -587,6 +587,8 @@ void __iomem *dev_request_mem_region(struct device *dev, int num)
>>  	struct resource *res;
>>  
>>  	res = dev_request_mem_resource(dev, num);
>> +	if (!IS_ERR(res) && WARN_ON(IS_ERR_VALUE(res->start)))
>> +		return IOMEM_ERR_PTR(res->start);
> 
> Which code can set res->start to an error value?

It can end up being an error value, because there is actual a MMIO
region at a high address. In that case, I'd rather we return an
error, so dev_request_mem_resource would need to be used instead.

Thanks,
Ahmad

> 
> Sascha
> 
>>  	if (IS_ERR(res))
>>  		return ERR_CAST(res);
>>  
>> diff --git a/include/linux/device.h b/include/linux/device.h
>> index 66294910abb3..661d8b24730e 100644
>> --- a/include/linux/device.h
>> +++ b/include/linux/device.h
>> @@ -39,7 +39,7 @@ static inline void __iomem *dev_platform_ioremap_resource(struct device *dev,
>>  	 * so we don't need to do anything besides requesting the regions
>>  	 * and can leave the memory attributes unchanged.
>>  	 */
>> -	return dev_request_mem_region_err_null(dev, resource);
>> +	return dev_request_mem_region(dev, resource);
>>  }
>>  
>>  static inline void __iomem *devm_ioremap(struct device *dev,
>> -- 
>> 2.39.5
>>
>>
>>
> 

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