| Message ID | 20090407082231.803193635@denx.de (mailing list archive) |
|---|---|
| State | Accepted, archived |
| Commit | c724d67dfff3bd547d2768b450af8d3b9f83bb27 |
| Delegated to: | Kumar Gala |
| Headers | show |
On Tue, Apr 7, 2009 at 1:20 AM, Wolfgang Grandegger <wg@grandegger.com> wrote: > Preserve I2C clock settings for the Socrates MPC8544 board. I had thought that the preserve-clocking property was intended for older boards that don't currently have any method of getting the clock setting out of u-boot. Since Socrates is a new board, U-Boot should probably be made to fill in the real clock rate setting. g. > > Signed-off-by: Wolfgang Grandegger <wg@grandegger.com> > --- > arch/powerpc/boot/dts/socrates.dts | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-) > > Index: linux-2.6-galak/arch/powerpc/boot/dts/socrates.dts > =================================================================== > --- linux-2.6-galak.orig/arch/powerpc/boot/dts/socrates.dts 2009-04-07 10:09:07.161718915 +0200 > +++ linux-2.6-galak/arch/powerpc/boot/dts/socrates.dts 2009-04-07 10:09:16.207719258 +0200 > @@ -79,11 +79,11 @@ > #address-cells = <1>; > #size-cells = <0>; > cell-index = <0>; > - compatible = "fsl-i2c"; > + compatible = "fsl,mpc8544-i2c", "fsl-i2c"; > reg = <0x3000 0x100>; > interrupts = <43 2>; > interrupt-parent = <&mpic>; > - dfsrr; > + fsl,preserve-clocking; > > dtt@28 { > compatible = "winbond,w83782d"; > @@ -111,11 +111,11 @@ > #address-cells = <1>; > #size-cells = <0>; > cell-index = <1>; > - compatible = "fsl-i2c"; > + compatible = "fsl,mpc8544-i2c", "fsl-i2c"; > reg = <0x3100 0x100>; > interrupts = <43 2>; > interrupt-parent = <&mpic>; > - dfsrr; > + fsl,preserve-clocking; > }; > > enet0: ethernet@24000 { > >
Grant Likely wrote: > On Tue, Apr 7, 2009 at 1:20 AM, Wolfgang Grandegger <wg@grandegger.com> wrote: >> Preserve I2C clock settings for the Socrates MPC8544 board. > > I had thought that the preserve-clocking property was intended for > older boards that don't currently have any method of getting the clock > setting out of u-boot. Since Socrates is a new board, U-Boot should > probably be made to fill in the real clock rate setting. I'm not sure if I understand what you mean. If an old version of U-Boot on an old board sets the I2C clock, it can be used (inherited) by Linux using the property "preserve-clocking". It is actually the customers choice to set the I2C clock in U-Boot and re-use it by Linux. Wolfgang.
On Wed, Apr 8, 2009 at 12:16 AM, Wolfgang Grandegger <wg@grandegger.com> wrote: > Grant Likely wrote: >> On Tue, Apr 7, 2009 at 1:20 AM, Wolfgang Grandegger <wg@grandegger.com> wrote: >>> Preserve I2C clock settings for the Socrates MPC8544 board. >> >> I had thought that the preserve-clocking property was intended for >> older boards that don't currently have any method of getting the clock >> setting out of u-boot. Since Socrates is a new board, U-Boot should >> probably be made to fill in the real clock rate setting. > > I'm not sure if I understand what you mean. If an old version of U-Boot > on an old board sets the I2C clock, it can be used (inherited) by Linux > using the property "preserve-clocking". > > It is actually the customers choice to set the I2C clock in U-Boot and > re-use it by Linux. Setting it in the register != recording the value in the device tree. I'm saying that since Socrates is a new board it should not use the preserve-clocking dirty trick (and it is a dirty trick) because the correct clocking data can be passed via the device tree. g.
Grant Likely wrote: > On Wed, Apr 8, 2009 at 12:16 AM, Wolfgang Grandegger <wg@grandegger.com> wrote: >> Grant Likely wrote: >>> On Tue, Apr 7, 2009 at 1:20 AM, Wolfgang Grandegger <wg@grandegger.com> wrote: >>>> Preserve I2C clock settings for the Socrates MPC8544 board. >>> I had thought that the preserve-clocking property was intended for >>> older boards that don't currently have any method of getting the clock >>> setting out of u-boot. Since Socrates is a new board, U-Boot should >>> probably be made to fill in the real clock rate setting. >> I'm not sure if I understand what you mean. If an old version of U-Boot >> on an old board sets the I2C clock, it can be used (inherited) by Linux >> using the property "preserve-clocking". >> >> It is actually the customers choice to set the I2C clock in U-Boot and >> re-use it by Linux. > > Setting it in the register != recording the value in the device tree. > I'm saying that since Socrates is a new board it should not use the > preserve-clocking dirty trick (and it is a dirty trick) because the > correct clocking data can be passed via the device tree. Why should an old board then use it. "fsl, preserve-clocking" is a new feature, like using "clock-frequency" and you have the choice to explicitly set the clocking via device tree or inherit it from the boot loader. So far, a fixed FDR/DFRSS value (0x1031) was written to the registers by Linux. Wolfgang.
On Apr 8, 2009, at 1:27 PM, Wolfgang Grandegger wrote: > Grant Likely wrote: >> On Wed, Apr 8, 2009 at 12:16 AM, Wolfgang Grandegger <wg@grandegger.com >> > wrote: >>> Grant Likely wrote: >>>> On Tue, Apr 7, 2009 at 1:20 AM, Wolfgang Grandegger <wg@grandegger.com >>>> > wrote: >>>>> Preserve I2C clock settings for the Socrates MPC8544 board. >>>> I had thought that the preserve-clocking property was intended for >>>> older boards that don't currently have any method of getting the >>>> clock >>>> setting out of u-boot. Since Socrates is a new board, U-Boot >>>> should >>>> probably be made to fill in the real clock rate setting. >>> I'm not sure if I understand what you mean. If an old version of U- >>> Boot >>> on an old board sets the I2C clock, it can be used (inherited) by >>> Linux >>> using the property "preserve-clocking". >>> >>> It is actually the customers choice to set the I2C clock in U-Boot >>> and >>> re-use it by Linux. >> >> Setting it in the register != recording the value in the device tree. >> I'm saying that since Socrates is a new board it should not use the >> preserve-clocking dirty trick (and it is a dirty trick) because the >> correct clocking data can be passed via the device tree. > > Why should an old board then use it. "fsl, preserve-clocking" is a new > feature, like using "clock-frequency" and you have the choice to > explicitly set the clocking via device tree or inherit it from the > boot > loader. So far, a fixed FDR/DFRSS value (0x1031) was written to the > registers by Linux. I think Grant's point is socrates is a new board with a new u-boot. That u-boot should be able to set the clock-frequency property in i2c. One assumes if you a clock-frequency property you wouldn't use "fsl,preserve-clocking". (However -- its feasible they are mutually exclusive). - k
Kumar Gala wrote: > > On Apr 8, 2009, at 1:27 PM, Wolfgang Grandegger wrote: > >> Grant Likely wrote: >>> On Wed, Apr 8, 2009 at 12:16 AM, Wolfgang Grandegger >>> <wg@grandegger.com> wrote: >>>> Grant Likely wrote: >>>>> On Tue, Apr 7, 2009 at 1:20 AM, Wolfgang Grandegger >>>>> <wg@grandegger.com> wrote: >>>>>> Preserve I2C clock settings for the Socrates MPC8544 board. >>>>> I had thought that the preserve-clocking property was intended for >>>>> older boards that don't currently have any method of getting the clock >>>>> setting out of u-boot. Since Socrates is a new board, U-Boot should >>>>> probably be made to fill in the real clock rate setting. >>>> I'm not sure if I understand what you mean. If an old version of U-Boot >>>> on an old board sets the I2C clock, it can be used (inherited) by Linux >>>> using the property "preserve-clocking". >>>> >>>> It is actually the customers choice to set the I2C clock in U-Boot and >>>> re-use it by Linux. >>> >>> Setting it in the register != recording the value in the device tree. >>> I'm saying that since Socrates is a new board it should not use the >>> preserve-clocking dirty trick (and it is a dirty trick) because the >>> correct clocking data can be passed via the device tree. >> >> Why should an old board then use it. "fsl, preserve-clocking" is a new >> feature, like using "clock-frequency" and you have the choice to >> explicitly set the clocking via device tree or inherit it from the boot >> loader. So far, a fixed FDR/DFRSS value (0x1031) was written to the >> registers by Linux. > > I think Grant's point is socrates is a new board with a new u-boot. > That u-boot should be able to set the clock-frequency property in i2c. > One assumes if you a clock-frequency property you wouldn't use > "fsl,preserve-clocking". (However -- its feasible they are mutually > exclusive). OK, now it makes more sense to me even if I never thought that way. My intention was to allow Linux to use a *different* frequency as the bootloader by specifying the "clock-frequency" property. This would not be possible with a fixup by the bootloader. Wolfgang.
Index: linux-2.6-galak/arch/powerpc/boot/dts/socrates.dts =================================================================== --- linux-2.6-galak.orig/arch/powerpc/boot/dts/socrates.dts 2009-04-07 10:09:07.161718915 +0200 +++ linux-2.6-galak/arch/powerpc/boot/dts/socrates.dts 2009-04-07 10:09:16.207719258 +0200 @@ -79,11 +79,11 @@ #address-cells = <1>; #size-cells = <0>; cell-index = <0>; - compatible = "fsl-i2c"; + compatible = "fsl,mpc8544-i2c", "fsl-i2c"; reg = <0x3000 0x100>; interrupts = <43 2>; interrupt-parent = <&mpic>; - dfsrr; + fsl,preserve-clocking; dtt@28 { compatible = "winbond,w83782d"; @@ -111,11 +111,11 @@ #address-cells = <1>; #size-cells = <0>; cell-index = <1>; - compatible = "fsl-i2c"; + compatible = "fsl,mpc8544-i2c", "fsl-i2c"; reg = <0x3100 0x100>; interrupts = <43 2>; interrupt-parent = <&mpic>; - dfsrr; + fsl,preserve-clocking; }; enet0: ethernet@24000 {
Preserve I2C clock settings for the Socrates MPC8544 board. Signed-off-by: Wolfgang Grandegger <wg@grandegger.com> --- arch/powerpc/boot/dts/socrates.dts | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-)