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Date: Thu, 9 Aug 2018 10:39:27 +0800 From: Yixun Lan <yixun.lan@...ogic.com> To: Jerome Brunet <jbrunet@...libre.com>, Stephen Boyd <sboyd@...nel.org>, Neil Armstrong <narmstrong@...libre.com> CC: <yixun.lan@...ogic.com>, Rob Herring <robh@...nel.org>, Martin Blumenstingl <martin.blumenstingl@...glemail.com>, Kevin Hilman <khilman@...libre.com>, Michael Turquette <mturquette@...libre.com>, <linux-kernel@...r.kernel.org>, Boris Brezillon <boris.brezillon@...tlin.com>, Liang Yang <liang.yang@...ogic.com>, Qiufang Dai <qiufang.dai@...ogic.com>, Miquel Raynal <miquel.raynal@...tlin.com>, Carlo Caione <carlo@...one.org>, <linux-amlogic@...ts.infradead.org>, <linux-clk@...r.kernel.org>, <linux-arm-kernel@...ts.infradead.org>, Jian Hu <jian.hu@...ogic.com> Subject: Re: [PATCH v3 2/2] clk: meson: add sub MMC clock controller driver 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 <jbrunet@...libre.com> >>>>>> + * >>>>>> + * Copyright (c) 2018 Amlogic, inc. >>>>>> + * Author: Yixun Lan <yixun.lan@...ogic.com> >>>>>> + */ >>>>>> + >>>>>> +#include <linux/clk.h> >>>>> >>>>> 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
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