Messages in this thread | | | From | Rajan Vaja <> | Subject | RE: [PATCH] clk: clk-fixed-factor: Use new macro CLK_OF_DECLARE_DRIVER | Date | Fri, 6 Jul 2018 10:54:34 +0000 |
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Hi Stephen,
> -----Original Message----- > From: Rajan Vaja > Sent: 04 June 2018 09:11 AM > To: 'Stephen Boyd' <sboyd@kernel.org> > Cc: linux-clk@vger.kernel.org; linux-kernel@vger.kernel.org; Jolly Shah > <JOLLYS@xilinx.com>; Michal Simek <michals@xilinx.com>; > mturquette@baylibre.com > Subject: RE: [PATCH] clk: clk-fixed-factor: Use new macro > CLK_OF_DECLARE_DRIVER > > Hi Stephen, > > Thanks for the reply. > > > -----Original Message----- > > From: Stephen Boyd [mailto:sboyd@kernel.org] > > Sent: 02 June 2018 12:11 PM > > To: Rajan Vaja <RAJANV@xilinx.com> > > Cc: linux-clk@vger.kernel.org; linux-kernel@vger.kernel.org; Jolly Shah > > <JOLLYS@xilinx.com>; Michal Simek <michals@xilinx.com>; > > mturquette@baylibre.com > > Subject: RE: [PATCH] clk: clk-fixed-factor: Use new macro > > CLK_OF_DECLARE_DRIVER > > > > Quoting Rajan Vaja (2018-05-03 02:18:30) > > > Hi Stephen, > > > > > > > -----Original Message----- > > > > From: Rajan Vaja > > > > Sent: 16 March 2018 05:20 PM > > > > To: 'Stephen Boyd' <sboyd@kernel.org> > > > > Cc: linux-clk@vger.kernel.org; linux-kernel@vger.kernel.org; Jolly Shah > > > > <JOLLYS@xilinx.com>; Michal Simek <michals@xilinx.com>; > > > > mturquette@baylibre.com > > > > Subject: RE: [PATCH] clk: clk-fixed-factor: Use new macro > > > > CLK_OF_DECLARE_DRIVER > > > > > > > > Hi Stephen, > > > > > > > > Thanks for the comment. > > > > > > > > > -----Original Message----- > > > > > From: Stephen Boyd [mailto:sboyd@kernel.org] > > > > > Sent: 16 March 2018 12:17 AM > > > > > To: Rajan Vaja <RAJANV@xilinx.com> > > > > > Cc: linux-clk@vger.kernel.org; linux-kernel@vger.kernel.org; Jolly Shah > > > > > <JOLLYS@xilinx.com>; Michal Simek <michals@xilinx.com>; > > > > > mturquette@baylibre.com > > > > > Subject: RE: [PATCH] clk: clk-fixed-factor: Use new macro > > > > > CLK_OF_DECLARE_DRIVER > > > > > > > > > > Quoting Rajan Vaja (2018-03-09 11:27:40) > > > > > > > From: Stephen Boyd [mailto:sboyd@kernel.org] > > > > > > > > > > > > > > Is the intent to register the clk twice? I believe things are working as > > > > > > > intended without this patch, so maybe you can explain a little more > > what > > > > > > > you're trying to fix. > > > > > > [Rajan] Yes. During of_clk_init() if some DT fixed factor clock has > > > > > > parent which is neither mentioned in output-clock-names of clock > > > > > > controller nor registered as clock provider, of_clk_init() will try to > > > > > > forcefully register in second loop. > > > > > > > > > > > > if (force || parent_ready(clk_provider->np)) { > > > > > > > > > > > > /* Don't populate platform devices */ > > > > > > of_node_set_flag(clk_provider->np, > > > > > > OF_POPULATED); > > > > > > > > > > > > So registration of this DT fixed-factor clock would fail as parent > > > > > > would be NULL as below (called from _of_fixed_factor_clk_setup()): > > > > > > parent_name = of_clk_get_parent_name(node, 0); > > > > > > > > > > > > On the other hand, even if registration failed, that node will be > > > > > > marked as OF_POPULATED, so probe of clk-fixed-factor.c will also not > > > > > > be called and that DT fixed-factor clock would never be registered. > > > > > > > > > > > > Same thing is discussed at https://lkml.org/lkml/2017/6/5/681 . > > > > > > > > > > Ok. I believe the answer is to fix the DT to describe the parent chain > > > > > properly with clock-output-names. Otherwise, we have no good way of > > > > > figuring out what the name should be. > > > > [Rajan] clock DT binding doc says that clock-output-names property > > > > is optional and sometimes not recommended. > > > > I think this patch fixes the issue we have which mandates to add clock- > > output- > > > > names > > > > property (for this particular case). Also, IIUC platform driver probe in clk- > > fixed- > > > > factor.c > > > > will never be called unless we use CLK_OF_DECLARE_DRIVER. > > > > I completely agree that proper solution would be to stop using strings to > > > > describe clock topology. > > > [Rajan] Any comments on this? > > > Unless we have proper solution ready, we need to have some mechanism to > > handle this scenario. > > > clock-output-names is optional and without this, it mandates to use clock- > > output-names. > > > > > > > I couldn't read your outlook sent email and I was too busy to go > > translate it. Some bug in my MUA it seems. > > > > Can you add the output-names property? In this case it's practically > > mandatory, so if you can't do it I'd like to hear why not. > [Rajan] In our case, we are firmware maintains clock database and driver query > clocks > from firmware and registers clock based on information received from > firmware. So > output clock names are not fixed. > https://patchwork.kernel.org/patch/10439893/ - dt-bindings: clock: Add > bindings for ZynqMP clock driver > https://patchwork.kernel.org/patch/10439891/ - drivers: clk: Add ZynqMP > clock driver [Rajan] Any comments?
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