Re: [PATCH RFC v9 0/8] mfd: ls2kbmc: multiple fixes for this driver

[Miao Wang]

Hi,

> 2026年9月22日 17:55，Binbin Zhou <zhoubinbin@xxxxxxxxxxx> 写道：
> 
> Hi:
> 
> On 2026/8/11 16:07, Miao Wang via B4 Relay wrote:
>> Previously, the driver has been introduced to support the Loongson 2K
>> BMC running on the Loongson Servers, which is essential to prevent
>> the system from hanging when the BMC is being reset and the default
>> efi-framebuffer is being used. However, there are some drawbacks in the
>> driver.
>> Firstly, the driver tries to read and write to the connected PCI-E host
>> controller registers, assuming that the BMC is connected to LS7A PCI-E
>> host controller. This assumption should be true for real products, but
>> to prevent from accidentally reading and writing to the wrong PCI-E host
>> controller, this driver should be modified to check this before
>> accessing the registers.
>> Secondly, the driver uses non-exported functions to tell the vt
>> subsystem to redraw the screen, preventing the driver from being
>> compiling as a module. This can be fixed by using the exported
>> functions instead.
>> Thirdly, the driver directly accesses the GPIO controller registers
>> using hard-coded addresses, which might conflict with the loaded GPIO
>> controller driver for the same GPIO controller. This is fixed in this
>> series by using the GPIO subsystem APIs instead. To associate a GPIO pin
>> with a certian PCI device, it should be declared in the firmware level,
>> i.e. in the ACPI table or the device tree, and thus the firmware
>> interface should be discussed and coordinated with Loongson personnels.
>> Despite of this, the proposed solution in this series should be the
>> minimum necessary change to express such association. Furthermore, the
>> conventional GPIO pin number and the controller address are also
>> provided, to be used as a fallback when the GPIO pin is not declared.
>> Finally, there is a minor issue in the driver where it changes the
>> mode string describing the screen resolution during probing, which
>> prevents the device from being probed again if -EPROBE_DEFER is
>> returned by the probe function.
>> I have tested the changes in this series on a single-socket Loongson
>> 3C6000 server with a Loongson 2K BMC, and the driver works as expected
>> when the corresponding GPIO driver is additionally loaded.
>> Signed-off-by: Miao Wang <shankerwangmiao@xxxxxxxxx>
>> ---
>> Changes in v9:
>> - Extend the kernel docs for gpio_device_get_fwnode() to describe the
>>   usage of this function, as suggested by Bartosz.
>> - Link to v8: https://lore.kernel.org/r/20260810-ls2kbmc-mod-v8-0-16e44f7322f4@xxxxxxxxx
> 
> I’m deeply sorry for the delayed response due to personal reasons.
> 
> Regarding Patch-1, I don’t mind using your current version as is—it’s more complete. However, I received another email from lkp[1] a few days ago, and I still hope this patch can be merged sooner.
> 
> The current discussion is focused on the GPIO-related patch, but in reality, it isn’t closely tied to the other patches; it’s more of an optimization. If possible, I personally think we could set it aside for now and treat it as a separate set of feature optimization patches.
> 
> [1]: https://lore.kernel.org/all/202608230816.ifMzE0No-lkp@xxxxxxxxx/

I'm not opposed to separating the first patch from the other patches.
But it seems that Bartosz has not been back ready for reviewing this
series.

Cheers,

Miao Wang