On Sunday 08 July 2018 17:02:20 Damien Thébault wrote: > Fix return code check for "max brightness" ACPI call. > > The dell laptop ACPI video brightness control is not present on dell > laptops anymore, but was present in older kernel versions. > > The code that checks the return value is incorrect since the SMM > refactoring. > > The old code was: > if (buffer->output[0] == 0) > > Which was changed to: > ret = dell_send_request(...) > if (ret) > > However, dell_send_request() will return 0 if buffer->output[0] == 0, > so we must change the check to: > if (ret == 0) You are right, dell_send_request() return non-zero value on error. > This issue was found on a Dell M4800 laptop, and the fix tested on it > as well. > > Fixes: 549b4930f057 ("dell-smbios: Introduce dispatcher for SMM calls") > Signed-off-by: Damien Thébault <damien@xxxxxxxx> > Tested-by: Damien Thébault <damien@xxxxxxxx> > --- > drivers/platform/x86/dell-laptop.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/platform/x86/dell-laptop.c > b/drivers/platform/x86/dell-laptop.c index f1fa8612db40..06978c14c83b > 100644 --- a/drivers/platform/x86/dell-laptop.c > +++ b/drivers/platform/x86/dell-laptop.c > @@ -2185,7 +2185,7 @@ static int __init dell_init(void) > dell_fill_request(&buffer, token->location, 0, 0, 0); > ret = dell_send_request(&buffer, > CLASS_TOKEN_READ, > SELECT_TOKEN_AC); > - if (ret) > + if (ret == 0) > max_intensity = buffer.output[3]; > } > Reviewed-by: Pali Rohár <pali.rohar@xxxxxxxxx> -- Pali Rohár pali.rohar@xxxxxxxxx
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