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[2.39.143.183]) by smtp.gmail.com with ESMTPSA id q14-20020a170906144e00b006feb047502bsm5116675ejc.151.2022.05.31.08.40.41 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 May 2022 08:40:42 -0700 (PDT) Date: Tue, 31 May 2022 17:40:40 +0200 From: Tommaso Merciai To: Jacopo Mondi Cc: linuxfancy@googlegroups.com, linux-amarula@amarulasolutions.com, michael@amarulasolutions.com, Shunqian Zheng , Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/4] media: i2c: ov5695: use regulator_bulk_enable/regulator_bulk disable instead of for loop Message-ID: <20220531154040.GA1331064@tom-ThinkPad-T14s-Gen-2i> References: <20220519075117.1003520-1-tommaso.merciai@amarulasolutions.com> <20220519075117.1003520-2-tommaso.merciai@amarulasolutions.com> <20220531131409.f54znvogejkwqqkf@uno.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220531131409.f54znvogejkwqqkf@uno.localdomain> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Jacopo, On Tue, May 31, 2022 at 03:14:09PM +0200, Jacopo Mondi wrote: > Hi Tommaso, > > On Thu, May 19, 2022 at 09:51:14AM +0200, Tommaso Merciai wrote: > > Enable regulator using regulator_bulk_enable/regulatore_bulk_disable > > function in __ov5695_power_on/__ov5695_power_off function instead of for loop. > > This reduce code size and make things more clear > > > > Signed-off-by: Tommaso Merciai > > Co-Developed-by: Michael Trimarchi > > --- > > drivers/media/i2c/ov5695.c | 25 +++++++------------------ > > 1 file changed, 7 insertions(+), 18 deletions(-) > > > > diff --git a/drivers/media/i2c/ov5695.c b/drivers/media/i2c/ov5695.c > > index 439385938a51..880b586e55fe 100644 > > --- a/drivers/media/i2c/ov5695.c > > +++ b/drivers/media/i2c/ov5695.c > > @@ -972,7 +972,7 @@ static int ov5695_s_stream(struct v4l2_subdev *sd, int on) > > > > static int __ov5695_power_on(struct ov5695 *ov5695) > > { > > - int i, ret; > > + int ret; > > struct device *dev = &ov5695->client->dev; > > > > ret = clk_prepare_enable(ov5695->xvclk); > > @@ -987,13 +987,10 @@ static int __ov5695_power_on(struct ov5695 *ov5695) > > * The hardware requires the regulators to be powered on in order, > > * so enable them one by one. > > */ > > The comment says that the hardware requires regulators to be enabled > in precise order > > > - for (i = 0; i < OV5695_NUM_SUPPLIES; i++) { > > - ret = regulator_enable(ov5695->supplies[i].consumer); > > - if (ret) { > > - dev_err(dev, "Failed to enable %s: %d\n", > > - ov5695->supplies[i].supply, ret); > > - goto disable_reg_clk; > > - } > > + ret = regulator_bulk_enable(ARRAY_SIZE(ov5695->supplies), ov5695->supplies); > > bulk_enable() uses the async API (async_schedule_domain() in > particular) which by the name makes me think such ordering guarantee > cannot be respected. > > However most sensors require some kind of ordering when enabling > regulators, and most of the use the bulk API anyhow. The fact this > driver uses the bulk API to get an release the regulators but not for > enabling them and the above comment, makes me think it has been done > on purpose ? Could you check with the driver author maybe ? Thanks for suggestion, good question. I see also ov5693 driver use bulk_enable/bulk_disable on ov5693_sensor_powerdown and ov5693_sensor_powerup functions, I take this as reference (and I'm wrong) In a functional test on PX30_Mini_evb_v11_20190507, after this series I'm able to see the correct chip id during probe and do some capture. I think you are right Jacopo, we can drop off this [PATCH 1/4] On the following link I found the issue that you describe: [1] > > > + if (ret) { > > + dev_err(dev, "Failed to enable regulators %d\n", ret); > > + goto disable_reg_clk; > > } > > > > gpiod_set_value_cansleep(ov5695->reset_gpio, 0); > > @@ -1003,8 +1000,7 @@ static int __ov5695_power_on(struct ov5695 *ov5695) > > return 0; > > > > disable_reg_clk: > > - for (--i; i >= 0; i--) > > - regulator_disable(ov5695->supplies[i].consumer); > > + regulator_bulk_disable(ARRAY_SIZE(ov5695->supplies), ov5695->supplies); > > FYI the bulk API does this for you if enabling any of the regulators fails. > Hence this should not be necessary. Thanks for sharing! This is new to me. I'll update the series on v2 removing this patch. Regards, Tommaso [1]: https://mailweb.openeuler.org/hyperkitty/list/kernel@openeuler.org/message/4X54QYJDRRE4K5BW4FTDZUGRAL4GRQWY/ > Thanks > j > > > clk_disable_unprepare(ov5695->xvclk); > > > > return ret; > > @@ -1012,8 +1008,6 @@ static int __ov5695_power_on(struct ov5695 *ov5695) > > > > static void __ov5695_power_off(struct ov5695 *ov5695) > > { > > - struct device *dev = &ov5695->client->dev; > > - int i, ret; > > > > clk_disable_unprepare(ov5695->xvclk); > > gpiod_set_value_cansleep(ov5695->reset_gpio, 1); > > @@ -1022,12 +1016,7 @@ static void __ov5695_power_off(struct ov5695 *ov5695) > > * The hardware requires the regulators to be powered off in order, > > * so disable them one by one. > > */ > > - for (i = OV5695_NUM_SUPPLIES - 1; i >= 0; i--) { > > - ret = regulator_disable(ov5695->supplies[i].consumer); > > - if (ret) > > - dev_err(dev, "Failed to disable %s: %d\n", > > - ov5695->supplies[i].supply, ret); > > - } > > + regulator_bulk_disable(ARRAY_SIZE(ov5695->supplies), ov5695->supplies); > > } > > > > static int __maybe_unused ov5695_runtime_resume(struct device *dev) > > -- > > 2.25.1 > > -- Tommaso Merciai Embedded Linux Engineer tommaso.merciai@amarulasolutions.com __________________________________ Amarula Solutions SRL Via Le Canevare 30, 31100 Treviso, Veneto, IT T. +39 042 243 5310 info@amarulasolutions.com www.amarulasolutions.com