Re: [PATCH -next] spi: stm32-qspi: Simpify resource lookup
From: Jinjie Ruan
Date: Fri Aug 23 2024 - 02:23:13 EST
On 2024/8/22 22:58, Mark Brown wrote:
> On Tue, Aug 20, 2024 at 08:37:07PM +0800, Jinjie Ruan wrote:
>> Use the devm_platform_ioremap_resource_byname() helper instead of
>> calling platform_get_resource_byname() and devm_ioremap_resource()
>> separately.
>
> This breaks boot on the Avenger96 board, it causes a NULL pointer
> dereference:
>
> [ 2.350480] Unable to handle kernel NULL pointer dereference at virtual address 00000000 when read
>
> ...
>
> [ 2.695787] Call trace:
> [ 2.695807] stm32_qspi_probe from platform_probe+0x5c/0xb0
> [ 2.703914] platform_probe from really_probe+0xc8/0x2c8
> [ 2.709284] really_probe from __driver_probe_device+0x88/0x19c
> [ 2.715145] __driver_probe_device from driver_probe_device+0x30/0x104
>
> https://lava.sirena.org.uk/scheduler/job/650792
>
>> - res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "qspi");
>> - qspi->io_base = devm_ioremap_resource(dev, res);
>> + qspi->io_base = devm_platform_ioremap_resource_byname(pdev, "qspi");
>> if (IS_ERR(qspi->io_base))
>> return PTR_ERR(qspi->io_base);
>>
>> qspi->phys_base = res->start;
>>
>> - res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "qspi_mm");
>> - qspi->mm_base = devm_ioremap_resource(dev, res);
>> + qspi->mm_base = devm_platform_ioremap_resource_byname(pdev, "qspi_mm");
>> if (IS_ERR(qspi->mm_base))
>> return PTR_ERR(qspi->mm_base);
>
> I can't identify any obvious error here, these look like a direct
> subsitution - the implementation of devm_platform_ioremap_resource_byname()
> looks to be the same as the replaced code and dev is set to &pdev->dev
> but I'm seeing the above behaviour.
Sorry, from lkp@xxxxxxxxx,I identify that the "res" returned by
platform_get_resource_byname() is used by "qspi->phys_base =
res->start;" later,so the devm_platform_ioremap_resource_byname() is not
inapplicable here.