Hi, On 10/17/23 13:14, Orlando Chamberlain wrote: > The data in the max brightness port for iMacs with MMIO gmux incorrectly > reports 0x03ff, but it should be 0xffff. As all other MMIO gmux models > have 0xffff, hard code this for all MMIO gmux's so they all have the > proper brightness range accessible. > > Reported-by: Karsten Leipold <poldi@xxxxxx> > Signed-off-by: Orlando Chamberlain <orlandoch.dev@xxxxxxxxx> Thank you for your patch/series, I've applied this patch (series) to the pdx86 fixes branch: https://git.kernel.org/pub/scm/linux/kernel/git/pdx86/platform-drivers-x86.git/log/?h=fixes I have added the following Fixes: tag while merging this: Fixes: 0c18184de990 ("platform/x86: apple-gmux: support MMIO gmux on T2 Macs") I will include this patch in my next fixes pull-req to Linus for the current kernel development cycle. Regards, Hans > --- > drivers/platform/x86/apple-gmux.c | 14 +++++++++++++- > 1 file changed, 13 insertions(+), 1 deletion(-) > > diff --git a/drivers/platform/x86/apple-gmux.c b/drivers/platform/x86/apple-gmux.c > index cadbb557a108..1417e230edbd 100644 > --- a/drivers/platform/x86/apple-gmux.c > +++ b/drivers/platform/x86/apple-gmux.c > @@ -105,6 +105,8 @@ struct apple_gmux_config { > #define GMUX_BRIGHTNESS_MASK 0x00ffffff > #define GMUX_MAX_BRIGHTNESS GMUX_BRIGHTNESS_MASK > > +# define MMIO_GMUX_MAX_BRIGHTNESS 0xffff > + > static u8 gmux_pio_read8(struct apple_gmux_data *gmux_data, int port) > { > return inb(gmux_data->iostart + port); > @@ -857,7 +859,17 @@ static int gmux_probe(struct pnp_dev *pnp, const struct pnp_device_id *id) > > memset(&props, 0, sizeof(props)); > props.type = BACKLIGHT_PLATFORM; > - props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS); > + > + /* > + * All MMIO gmux's have 0xffff as max brightness, but some iMacs incorrectly > + * report 0x03ff, despite the firmware being happy to set 0xffff as the brightness > + * at boot. Force 0xffff for all MMIO gmux's so they all have the correct brightness > + * range. > + */ > + if (type == APPLE_GMUX_TYPE_MMIO) > + props.max_brightness = MMIO_GMUX_MAX_BRIGHTNESS; > + else > + props.max_brightness = gmux_read32(gmux_data, GMUX_PORT_MAX_BRIGHTNESS); > > #if IS_REACHABLE(CONFIG_ACPI_VIDEO) > register_bdev = acpi_video_get_backlight_type() == acpi_backlight_apple_gmux;
