Re: [PATCH v2] Expose PCIe SSD Status LED Management DSM in sysfs

[Christoph Hellwig <hch@infradead.org>]

On Tue, Nov 10, 2020 at 09:37:35AM -0600, Stuart Hayes wrote:
> +Date:		October 2020
> +Contact:	Stuart Hayes <stuart.w.hayes@gmail.com>
> +Description:	If the device supports the ACPI _DSM method to control the
> +		PCIe SSD LED states, ssdleds_supported_states (read only)
> +		will show the LED states that are supported by the _DSM.
> +
> +What:		/sys/bus/pci/devices/.../ssdleds_current_state
> +Date:		October 2020
> +Contact:	Stuart Hayes <stuart.w.hayes@gmail.com>
> +Description:	If the device supports the ACPI _DSM method to control the
> +		PCIe SSD LED states, ssdleds_current_state will show or set
> +		the current LED states that are active.

Is the supported file really required?  Doesn't the current_state one
also show which LEDs exist?

> +config PCI_SSDLEDS
> +	def_bool y if (ACPI && PCI)
> +	depends on PCI && ACPI

We really should not default new code to y.

> +	if (dsm_output->status != 0 &&
> +	    !(dsm_output->status == 4 && dsm_output->function_specific_err == 1)) {

overly longline.  But to make this a little more obvious, maybe you
want to

 a) switch on dsm_output->status
 b) add symbolic names for the magic numbers