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Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.3.0 MIME-Version: 1.0 In-Reply-To: <154356023767.88331.18401188808548429052@swboyd.mtv.corp.google.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181130_010013_392687_8048B60E X-CRM114-Status: GOOD ( 21.25 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , devicetree@vger.kernel.org, Sean Wang , David Airlie , Michael Turquette , Sean Wang , Stephen Boyd , "linux-kernel@vger.kernel.org" , dri-devel , Ulrich Hecht , Chen-Yu Tsai , Randy Dunlap , Laurent Pinchart , Philipp Zabel , matthias.bgg@kernel.org, CK Hu , linux-mediatek@lists.infradead.org, linux-clk , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 30/11/2018 07:43, Stephen Boyd wrote: > Quoting Matthias Brugger (2018-11-21 09:09:52) >> >> >> On 21/11/2018 17:46, Stephen Boyd wrote: >>> Quoting Rob Herring (2018-11-19 11:15:16) >>>> On Sun, Nov 18, 2018 at 11:12 AM Matthias Brugger >>>> wrote: >>>>> On 11/17/18 12:15 AM, Rob Herring wrote: >>>>>> On Fri, Nov 16, 2018 at 01:54:45PM +0100, matthias.bgg@kernel.org wrote: >>>>>>> - #clock-cells = <1>; >>>>>>> + >>>>>>> + mmsys_clk: clock-controller@14000000 { >>>>>>> + compatible = "mediatek,mt2712-mmsys-clk"; >>>>>>> + #clock-cells = <1>; >>>>>> >>>>>> This goes against the general direction of not defining separate nodes >>>>>> for providers with no resources. >>>>>> >>>>>> Why do you need this and what does it buy if you have to continue to >>>>>> support the existing chips? >>>>>> >>>>> >>>>> It would show explicitly that the mmsys block is used to probe two >>>>> drivers, one for the gpu and one for the clocks. Otherwise that is >>>>> hidden in the drm driver code. I think it is cleaner to describe that in >>>>> the device tree. >>>> >>>> No, that's maybe cleaner for the driver implementation in the Linux >>>> kernel. What about other OS's or when Linux drivers and subsystems >>>> needs change? Cleaner for DT is design bindings that reflect the h/w. >>>> Hardware is sometimes just messy. >>>> >>> >>> I agree. I fail to see what this patch series is doing besides changing >>> driver probe and device creation methods and making a backwards >>> incompatible change to DT. Is there any other benefit here? >>> >> >> You are referring whole series? >> Citing the cover letter: >> "MMSYS in Mediatek SoCs has some registers to control clock gates (which is >> used in the clk driver) and some registers to set the routing and enable >> the differnet (sic!) blocks of the display subsystem. >> >> Up to now both drivers, clock and drm are probed with the same device tree >> compatible. But only the first driver get probed, which in effect breaks >> graphics on mt8173 and mt2701. > > Ouch! > Yes :) >> >> This patch uses a platform device registration in the DRM driver, which >> will trigger the probe of the corresponding clock driver. It was tested on the >> bananapi-r2 and the Acer R13 Chromebook." > > Alright, please don't add nodes in DT just to make device drivers probe. > Instead, register clks from the drm driver or create a child platform > device for the clk bits purely in the drm driver and have that probe the > associated clk driver from there. > I'll make the other SoCs probe via a child platform device from the drm driver, as already done in 2/12 and 3/12. Regards, Matthias >> >> DT is broken right now, because two drivers rely on the same node, which gets >> consumed just once. The new DT introduced does not break anything because it is >> only used for boards that: "[..] are not available to the general public >> (mt2712e) or only have the mmsys clock driver part implemented (mt6797)." > > Ok, so backwards compatibility is irrelevant then. Sounds fine to me. > > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel