| Message ID | 1474977426-3272-9-git-send-email-noralf@tronnes.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> Noralf Trønnes <noralf@tronnes.org> hat am 27. September 2016 um 13:57 > geschrieben: > > > i2c2 is connected to the HDMI connector and is controlled by the > firmware. Disable it to stay out of harms way. Until this point the commit message is okay, the rest is more confusing. Btw this should avoid a warning about missing clock frequency. > > From the downstream commit: > i2c-bcm2708/BCM270X_DT: Add support for I2C2 > > The third I2C bus (I2C2) is normally reserved for HDMI use. Careless > use of this bus can break an attached display - use with caution. > > It is recommended to disable accesses by VideoCore by setting > hdmi_ignore_edid=1 or hdmi_edid_file=1 in config.txt. > > Signed-off-by: Noralf Trønnes <noralf@tronnes.org> > --- > arch/arm/boot/dts/bcm2835-rpi.dtsi | 4 ---- > 1 file changed, 4 deletions(-) > > diff --git a/arch/arm/boot/dts/bcm2835-rpi.dtsi > b/arch/arm/boot/dts/bcm2835-rpi.dtsi > index e9b47b2..8bffbee 100644 > --- a/arch/arm/boot/dts/bcm2835-rpi.dtsi > +++ b/arch/arm/boot/dts/bcm2835-rpi.dtsi > @@ -59,10 +59,6 @@ > clock-frequency = <100000>; > }; > > -&i2c2 { > - status = "okay"; > -}; > - I'm not sure if this the right fix. According to bcm283x.dtsi the 3 i2c busses have the same compatible string "brcm,bcm2835-i2c", but the changelog suggests that this bus is "special". Shouldn't we use a different compatible string? Our intention isn't to disable i2c2 but avoid any claims of the usual i2c driver. > &sdhci { > status = "okay"; > bus-width = <4>; > -- > 2.8.2 > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
Am 27.09.2016 um 19:25 schrieb Stefan Wahren: > >> Noralf Trønnes <noralf@tronnes.org> hat am 27. September 2016 um 13:57 >> geschrieben: >> >> >> i2c2 is connected to the HDMI connector and is controlled by the >> firmware. Disable it to stay out of harms way. > > Until this point the commit message is okay, the rest is more confusing. > > Btw this should avoid a warning about missing clock frequency. > >> >> From the downstream commit: >> i2c-bcm2708/BCM270X_DT: Add support for I2C2 >> >> The third I2C bus (I2C2) is normally reserved for HDMI use. Careless >> use of this bus can break an attached display - use with caution. >> >> It is recommended to disable accesses by VideoCore by setting >> hdmi_ignore_edid=1 or hdmi_edid_file=1 in config.txt. >> >> Signed-off-by: Noralf Trønnes <noralf@tronnes.org> >> --- >> arch/arm/boot/dts/bcm2835-rpi.dtsi | 4 ---- >> 1 file changed, 4 deletions(-) >> >> diff --git a/arch/arm/boot/dts/bcm2835-rpi.dtsi >> b/arch/arm/boot/dts/bcm2835-rpi.dtsi >> index e9b47b2..8bffbee 100644 >> --- a/arch/arm/boot/dts/bcm2835-rpi.dtsi >> +++ b/arch/arm/boot/dts/bcm2835-rpi.dtsi >> @@ -59,10 +59,6 @@ >> clock-frequency = <100000>; >> }; >> >> -&i2c2 { >> - status = "okay"; >> -}; >> - > > I'm not sure if this the right fix. According to bcm283x.dtsi the 3 i2c busses > have the same compatible string "brcm,bcm2835-i2c", but the changelog suggests > that this bus is "special". > > Shouldn't we use a different compatible string? Our intention isn't to disable > i2c2 but avoid any claims of the usual i2c driver. > i2c2 should not be generally disabled. There's dtparam=i2c2_iknowwhatimdoing which enables CPU access to this bus. It's useful for reading out the monitor EDID by the CPU, and for accessing controls (backlight, volume) on certain monitors. And I have a I2C touchscreen controller on HDMI DDC. >> &sdhci { >> status = "okay"; >> bus-width = <4>; >> -- >> 2.8.2 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > -- > To unsubscribe from this list: send the line "unsubscribe linux-i2c" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >
Den 27.09.2016 19:25, skrev Stefan Wahren: >> Noralf Trønnes <noralf@tronnes.org> hat am 27. September 2016 um 13:57 >> geschrieben: >> >> >> i2c2 is connected to the HDMI connector and is controlled by the >> firmware. Disable it to stay out of harms way. > Until this point the commit message is okay, the rest is more confusing. > > Btw this should avoid a warning about missing clock frequency. > >> From the downstream commit: >> i2c-bcm2708/BCM270X_DT: Add support for I2C2 >> >> The third I2C bus (I2C2) is normally reserved for HDMI use. Careless >> use of this bus can break an attached display - use with caution. >> >> It is recommended to disable accesses by VideoCore by setting >> hdmi_ignore_edid=1 or hdmi_edid_file=1 in config.txt. >> >> Signed-off-by: Noralf Trønnes <noralf@tronnes.org> >> --- >> arch/arm/boot/dts/bcm2835-rpi.dtsi | 4 ---- >> 1 file changed, 4 deletions(-) >> >> diff --git a/arch/arm/boot/dts/bcm2835-rpi.dtsi >> b/arch/arm/boot/dts/bcm2835-rpi.dtsi >> index e9b47b2..8bffbee 100644 >> --- a/arch/arm/boot/dts/bcm2835-rpi.dtsi >> +++ b/arch/arm/boot/dts/bcm2835-rpi.dtsi >> @@ -59,10 +59,6 @@ >> clock-frequency = <100000>; >> }; >> >> -&i2c2 { >> - status = "okay"; >> -}; >> - > I'm not sure if this the right fix. According to bcm283x.dtsi the 3 i2c busses > have the same compatible string "brcm,bcm2835-i2c", but the changelog suggests > that this bus is "special". I just rounded up all the differences from downstream that I knew about into this patchset. But looking closer I see that the vc4 driver uses i2c2. So I'll drop this patch. Noralf. > Shouldn't we use a different compatible string? Our intention isn't to disable > i2c2 but avoid any claims of the usual i2c driver. > >> &sdhci { >> status = "okay"; >> bus-width = <4>; >> -- >> 2.8.2 >> >> >> _______________________________________________ >> linux-arm-kernel mailing list >> linux-arm-kernel@lists.infradead.org >> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
diff --git a/arch/arm/boot/dts/bcm2835-rpi.dtsi b/arch/arm/boot/dts/bcm2835-rpi.dtsi index e9b47b2..8bffbee 100644 --- a/arch/arm/boot/dts/bcm2835-rpi.dtsi +++ b/arch/arm/boot/dts/bcm2835-rpi.dtsi @@ -59,10 +59,6 @@ clock-frequency = <100000>; }; -&i2c2 { - status = "okay"; -}; - &sdhci { status = "okay"; bus-width = <4>;
i2c2 is connected to the HDMI connector and is controlled by the firmware. Disable it to stay out of harms way. From the downstream commit: i2c-bcm2708/BCM270X_DT: Add support for I2C2 The third I2C bus (I2C2) is normally reserved for HDMI use. Careless use of this bus can break an attached display - use with caution. It is recommended to disable accesses by VideoCore by setting hdmi_ignore_edid=1 or hdmi_edid_file=1 in config.txt. Signed-off-by: Noralf Trønnes <noralf@tronnes.org> --- arch/arm/boot/dts/bcm2835-rpi.dtsi | 4 ---- 1 file changed, 4 deletions(-)