From: Taniya Das <firstname.lastname@example.org> To: Stephen Boyd <email@example.com>, Michael Turquette <firstname.lastname@example.org> Cc: Andy Gross <email@example.com>, David Brown <firstname.lastname@example.org>, Rajendra Nayak <email@example.com>, firstname.lastname@example.org, email@example.com, firstname.lastname@example.org, email@example.com Subject: Re: [PATCH v6] clk: qcom: Add lpass clock controller driver for SDM845 Date: Wed, 17 Oct 2018 17:07:29 +0530 [thread overview] Message-ID: <firstname.lastname@example.org> (raw) In-Reply-To: <email@example.com> Hello Stephen, On 10/12/2018 11:05 PM, Stephen Boyd wrote: > Quoting Taniya Das (2018-10-09 23:12:27) >> >> >> On 10/10/2018 2:22 AM, Stephen Boyd wrote: >>> Quoting Taniya Das (2018-10-09 10:26:38) >>>> Hello Stephen, >>>> >>>> On 10/8/2018 8:14 AM, Stephen Boyd wrote: >>>>> Quoting Taniya Das (2018-10-04 05:02:26) >>>>>> Add support for the lpass clock controller found on SDM845 based devices. >>>>>> This would allow lpass peripheral loader drivers to control the clocks to >>>>>> bring the subsystem out of reset. >>>>>> LPASS clocks present on the global clock controller would be registered >>>>>> with the clock framework based on the device tree flag. Also do not gate >>>>>> these clocks if they are left unused. >>>>> >>>>> Why not gate them? This statement states what the code is doing, not why >>>>> it's doing it which is the more crucial information that should be >>>>> described in the commit text. Also, please add a comment about it to the >>>>> code next to the flag. >>>>> >>>>> I am concerned that it doesn't make any sense though, so probably it >>>>> shouldn't be marked as CLK_IGNORE_UNUSED and it's papering over some >>>>> other larger bug that needs to be fixed. >>>>> >>>> >>>> It does not have any bug, it is just that to access these lpass >>>> registers we would need the GCC lpass registers to be enabled. I would >>>> update the same in the commit text. >>>> >>>> During clock late_init these clocks should not be accessed to check the >>>> clock status as they would result in unclocked access. The client would >>>> request these clocks in the correct order and it would not have any issue. >>>> >>> >>> That seems like the bug right there. If the LPASS registers can't be >>> accessed unless the clks in GCC are enabled then this driver needs to >>> turn the clks on before reading/writing registers. Marking the clks as >>> ignore unused is skipping around the real problem. >>> >> >> If the driver requests for the clocks they would maintain the order. But >> if the clock late init call is invoked before the driver requests, there >> is no way I could manage this dependency, that is the only reason to >> mark them unused. >> > > Which driver are we talking about here? The lpass clk driver? Presumably > the lpass clk driver would request the GCC clks and turn them on in > probe and then register any lpass clks. If the lpass clk driver probes > bfeore late init, then the gcc clks will be enabled and everything > works, and if the lpass clk driver probes after late init then the clks > that can't be touched without gcc clks enabled won't be registered, and > then they won't be touched. What goes wrong? > > Okay, sure, I will take the GCC clock handles and then enable/disable them accordingly. -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation. --
next prev parent reply other threads:[~2018-10-17 11:37 UTC|newest] Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-10-04 12:02 [PATCH v6] Add support for LPASS clock controller " Taniya Das 2018-10-04 12:02 ` [PATCH v6] clk: qcom: Add lpass clock controller driver " Taniya Das 2018-10-08 2:44 ` Stephen Boyd 2018-10-09 17:26 ` Taniya Das 2018-10-09 20:52 ` Stephen Boyd 2018-10-10 6:12 ` Taniya Das 2018-10-12 17:35 ` Stephen Boyd 2018-10-17 11:37 ` Taniya Das [this message] 2018-10-17 12:04 ` Taniya Das 2018-10-17 14:20 ` Stephen Boyd 2018-10-19 10:39 ` Taniya Das 2018-10-25 10:51 ` tdas 2018-10-29 18:44 ` Stephen Boyd
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