On Wed, Dec 04, 2013 at 10:34:17AM -0700, Stephen Warren wrote: > On 12/04/2013 01:48 AM, Thierry Reding wrote: > > On Tue, Dec 03, 2013 at 11:31:00AM -0700, Stephen Warren wrote: > >> On 12/02/2013 01:52 AM, Thierry Reding wrote: > >>> On Sun, Dec 01, 2013 at 12:05:44PM -0700, Stephen Warren > >>> wrote: > >>>> On 11/29/2013 04:49 AM, Thierry Reding wrote: > >>>>> On Fri, Nov 15, 2013 at 01:53:56PM -0700, Stephen Warren > >>>>> wrote: [...] > >>>>>> @@ -60,6 +81,12 @@ of the following host1x client > >>>>>> modules: - compatible: "nvidia,tegra<chip>-dc" - reg: > >>>>>> Physical base address and length of the controller's > >>>>>> registers. - interrupts: The interrupt outputs from the > >>>>>> controller. + - clocks : Must contain an entry for each > >>>>>> entry in clock-names. + See > >>>>>> ../clocks/clock-bindings.txt for details. + - > >>>>>> clock-names : Must include the following entries: + - > >>>>>> disp1 or disp2 (depending on the controller instance) > >>>>> > >>>>> I'm not sure if this makes sense. The name could be the > >>>>> same independent of which controller uses it. If it isn't > >>>>> then the driver would need additional code to find out > >>>>> which instance it is and construct a dynamic string. > >>>>> > >>>>> Any objection to just make this entry "disp", or "dc"? > >>>> > >>>> This patch simply documents the binding that the various > >>>> drivers already require and/or whatever is already in the DT > >>>> files if there are any clocks the drivers don't currently > >>>> use. I did consider fixing up all the current usage to > >>>> actually be sane, but that would require even more driver > >>>> changes (in addition to those required for the reset > >>>> framework patches). > >>> > >>> Okay, I understand. I still think we should change the usage > >>> for this particular use-case subsequently. In retrospect the > >>> entry in clock-names wasn't thought out very well. It seems > >>> like the reason for using disp1 and disp2 respectively was so > >>> that it would match the system-wide clock name, rather than > >>> the clock's label within the display controller's context. > >>> > >>> Just to clarify what I mean, if we stick to the above, then > >>> we'll need to add code to the driver along the lines of: > >>> > >>> char clock_name[6]; > >>> > >>> if (regs->start == 0x54200000) index = 1; else index = 2; > >>> > >>> sprintf(clock_name, "disp%u", index); > >>> > >>> clk = devm_clk_get(&pdev->dev, clock_name); > >>> > >>> rather than the much more simple and elegant: > >>> > >>> clk = devm_clk_get(&pdev->dev, "disp"); > >>> > >>> The whole purpose of the clock consumer ID is to be generic > >>> and as such independent of the specific IP block or instance > >>> thereof. > >> > >> I think if the code needs this clock, I'd be tempted to do the > >> following: > >> > >> clk = clk_get(dev, "disp1"); if (IS_ERR(clk) && PTR_ERR(clk) != > >> -EPROBE_DEFERRED) clk = clk_get(dev, "disp2"); if (IS_ERR(clk)) > >> return PTR_ERR(clk); > >> > >> That avoids having to hard-code IP block base addresses and > >> construct clock names at run-time. > > > > I think perhaps we're getting our wires crossed. What I've been > > trying to say is that I think the binding should define the first > > clock to be named simply "disp". > > > > The reason why I think "disp" is a better choice than "disp1" and > > "disp2" is that it merely encodes the purpose of the clock for the > > display controller, and doesn't contain knowledge about the > > particular instance of the display controller. That's analogous to > > I2C or SPI nodes where the clock isn't named "i2c1", "i2c2", ... > > or "spi1", "spi2", ... but simply "i2c" or "spi" respectively. > > > > I know that existing DTS files use "disp1" and "disp2", > > respectively, but I think that was a wrong choice back at the time > > and therefore I suggest that we change it while we still can (DTS > > files are changing in 3.14 anyway because of the reset and DMA > > binding updates). > > > > Is that any clearer than what I was saying before? > > No, because I know what you meant before:-) > > The thing I was missing is that the existing disp1/disp2 naming is > /only/ something that's in the DT. The driver (and hence the exiting > as-yet-undocumented ABI) looks up this clock as "index 0" not as "name > disp1". Hence, we /can/ change the documented name without affecting > the ABI at all, and not affecting the ABI is something I was trying to > avoid in this patch. Excellent. Glad we're finally on the same page. > So, how about I fold the following into this patch: > > > diff --git a/Documentation/devicetree/bindings/gpu/nvidia,tegra20-host1x.txt b/Documentation/devicetree/bindings/gpu/nvidia,tegra20-host1x.txt > > index 42fe3a498e71..ab45c02aa658 100644 > > --- a/Documentation/devicetree/bindings/gpu/nvidia,tegra20-host1x.txt > > +++ b/Documentation/devicetree/bindings/gpu/nvidia,tegra20-host1x.txt > > @@ -111,7 +111,7 @@ of the following host1x client modules: > > - clocks: Must contain an entry for each entry in clock-names. > > See ../clocks/clock-bindings.txt for details. > > - clock-names: Must include the following entries: > > - - disp1 or disp2 (depending on the controller instance) > > + - dc > > This MUST be the first entry. > > - parent > > - resets: Must contain an entry for each entry in reset-names. > > diff --git a/arch/arm/boot/dts/tegra20.dtsi b/arch/arm/boot/dts/tegra20.dtsi > > index 01c20c7dbb51..648c494e927f 100644 > > --- a/arch/arm/boot/dts/tegra20.dtsi > > +++ b/arch/arm/boot/dts/tegra20.dtsi > > @@ -89,7 +89,7 @@ > > interrupts = <GIC_SPI 73 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&tegra_car TEGRA20_CLK_DISP1>, > > <&tegra_car TEGRA20_CLK_PLL_P>; > > - clock-names = "disp1", "parent"; > > + clock-names = "dc", "parent"; > > resets = <&tegra_car 27>; > > reset-names = "dc"; > > > > @@ -104,7 +104,7 @@ > > interrupts = <GIC_SPI 74 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&tegra_car TEGRA20_CLK_DISP2>, > > <&tegra_car TEGRA20_CLK_PLL_P>; > > - clock-names = "disp2", "parent"; > > + clock-names = "dc", "parent"; > > resets = <&tegra_car 26>; > > reset-names = "dc"; > > > > diff --git a/arch/arm/boot/dts/tegra30.dtsi b/arch/arm/boot/dts/tegra30.dtsi > > index 58a3dca24c49..829eb4b5091d 100644 > > --- a/arch/arm/boot/dts/tegra30.dtsi > > +++ b/arch/arm/boot/dts/tegra30.dtsi > > @@ -165,7 +165,7 @@ > > interrupts = <GIC_SPI 73 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&tegra_car TEGRA30_CLK_DISP1>, > > <&tegra_car TEGRA30_CLK_PLL_P>; > > - clock-names = "disp1", "parent"; > > + clock-names = "dc", "parent"; > > resets = <&tegra_car 27>; > > reset-names = "dc"; > > > > @@ -180,7 +180,7 @@ > > interrupts = <GIC_SPI 74 IRQ_TYPE_LEVEL_HIGH>; > > clocks = <&tegra_car TEGRA30_CLK_DISP2>, > > <&tegra_car TEGRA30_CLK_PLL_P>; > > - clock-names = "disp2", "parent"; > > + clock-names = "dc", "parent"; > > resets = <&tegra_car 26>; > > reset-names = "dc"; > > That looks perfect. Thanks! Thierry
Attachment:
pgpRvNnApPPZh.pgp
Description: PGP signature
