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. 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"; > -- To unsubscribe from this list: send the line "unsubscribe linux-tegra" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
