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SubjectRe: [PATCH 4.19 309/639] hwmon: (w83627hf) Use request_muxed_region for Super-IO accesses
Hi!
> [ Upstream commit e95fd518d05bfc087da6fcdea4900a57cfb083bd ]
>
> Super-IO accesses may fail on a system with no or unmapped LPC bus.
>
> Also, other drivers may attempt to access the LPC bus at the same time,
> resulting in undefined behavior.
>
> Use request_muxed_region() to ensure that IO access on the requested
> address space is supported, and to ensure that access by multiple drivers
> is synchronized.
>

> @@ -1644,9 +1654,21 @@ static int w83627thf_read_gpio5(struct platform_device *pdev)
> struct w83627hf_sio_data *sio_data = dev_get_platdata(&pdev->dev);
> int res = 0xff, sel;
>
> - superio_enter(sio_data);
> + if (superio_enter(sio_data)) {
> + /*
> + * Some other driver reserved the address space for itself.
> + * We don't want to fail driver instantiation because of that,
> + * so display a warning and keep going.
> + */
> + dev_warn(&pdev->dev,
> + "Can not read VID data: Failed to enable SuperIO access\n");
> + return res;
> + }
> +
> superio_select(sio_data, W83627HF_LD_GPIO5);
>
> + res = 0xff;
> +

This is strange. res is not actually assigned in the code above, so we
have res = 0xff twice. Can we remove one of the initializations and do
'return 0xff' directly to make code more clear?


> @@ -1677,7 +1699,17 @@ static int w83687thf_read_vid(struct platform_device *pdev)
> struct w83627hf_sio_data *sio_data = dev_get_platdata(&pdev->dev);
> int res = 0xff;
>
> - superio_enter(sio_data);
> + if (superio_enter(sio_data)) {
> + /*
> + * Some other driver reserved the address space for itself.
> + * We don't want to fail driver instantiation because of that,
> + * so display a warning and keep going.
> + */
> + dev_warn(&pdev->dev,
> + "Can not read VID data: Failed to enable SuperIO access\n");
> + return res;
> + }

Direct "return 0xff" would make more sense here, too.

Best regards,
Pavel
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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