From mboxrd@z Thu Jan 1 00:00:00 1970 From: yixun.lan@amlogic.com (Yixun Lan) Date: Thu, 9 Aug 2018 10:39:27 +0800 Subject: [PATCH v3 2/2] clk: meson: add sub MMC clock controller driver In-Reply-To: References: <20180712211244.11428-1-yixun.lan@amlogic.com> <20180712211244.11428-3-yixun.lan@amlogic.com> <153261840298.48062.2497103873681297587@swboyd.mtv.corp.google.com> <153270970080.48062.18399022907046343950@swboyd.mtv.corp.google.com> <153270995155.48062.4302847978258086624@swboyd.mtv.corp.google.com> Message-ID: <1e5f7ba3-59c1-27c8-89b7-cce87659462e@amlogic.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Hi Jerome On 07/30/18 16:57, Jerome Brunet wrote: > On Fri, 2018-07-27 at 09:45 -0700, Stephen Boyd wrote: >> Quoting Stephen Boyd (2018-07-27 09:41:40) >>> Quoting Yixun Lan (2018-07-27 07:52:23) >>>> HI Stephen: >>>> >>>> On 07/26/2018 11:20 PM, Stephen Boyd wrote: >>>>> Quoting Yixun Lan (2018-07-12 14:12:44) >>>>>> diff --git a/drivers/clk/meson/mmc-clkc.c b/drivers/clk/meson/mmc-clkc.c >>>>>> new file mode 100644 >>>>>> index 000000000000..36c4c7cd69a6 >>>>>> --- /dev/null >>>>>> +++ b/drivers/clk/meson/mmc-clkc.c >>>>>> @@ -0,0 +1,367 @@ >>>>>> +// SPDX-License-Identifier: (GPL-2.0+ OR MIT) >>>>>> +/* >>>>>> + * Amlogic Meson MMC Sub Clock Controller Driver >>>>>> + * >>>>>> + * Copyright (c) 2017 Baylibre SAS. >>>>>> + * Author: Jerome Brunet >>>>>> + * >>>>>> + * Copyright (c) 2018 Amlogic, inc. >>>>>> + * Author: Yixun Lan >>>>>> + */ >>>>>> + >>>>>> +#include >>>>> >>>>> Is this include used? >>>>> >>>> >>>> this is needed by clk_get_rate() >>>> see drivers/clk/meson/mmc-clkc.c:204 >>> >>> Hmm ok. That's unfortunate. >> >> You should be able to read the hardware to figure out the clk frequency? >> This may be a sign that the phase clk_ops are bad and should be passing >> in the frequency of the parent clk to the op so that phase can be >> calculated. Jerome? >> > > It could be a away to do it but: > a) if we modify the API, we would need to update every clock driver using it. > There is not that many users of the phase API but still, it is annoying > b) This particular driver need the parent rate, other might need something else > I guess. (parent phase ??, duty cycle ??) > > I think the real problem here it that you are using the consumer API. You should > be using the provider API like clk_hw_get_rate. Look at the clk-divider.c which > use clk_hw_round_rate() on the parent clock. I will replace it with clk_hw_get_rate() > > Clock drivers should deal with 'struct clk_hw', not 'struct clk'. I think it was > mentioned in the past that the 'clk' within 'struct clk_hw' might be removed > someday. > > Yixun, please don't put your clock driver within the controller driver. Please > implement your 'phase-delay' clock in its own file and export the ops, like > every other clock in the amlogic directory. Also, please review your list of > '#define', some of them are unnecessary copy/paste from the MMC driver. > will implement a clk-phase-delay.c I can move the extra CC list Yixun