linux-kernel - Re: [PATCH v8 20/34] mmc: sdhci-tegra: Add runtime PM and OPP support

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Message-ID: <YR+TgfCHKOPS3Ng8@orome.fritz.box>
Date:   Fri, 20 Aug 2021 13:35:29 +0200
From:   Thierry Reding <thierry.reding@...il.com>
To:     Dmitry Osipenko <digetx@...il.com>
Cc:     Jonathan Hunter <jonathanh@...dia.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Viresh Kumar <vireshk@...nel.org>,
        Stephen Boyd <sboyd@...nel.org>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        Mikko Perttunen <mperttunen@...dia.com>,
        Peter Chen <peter.chen@...nel.org>,
        Mark Brown <broonie@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>, Nishanth Menon <nm@...com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Richard Weinberger <richard@....at>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Lucas Stach <dev@...xeye.de>, Stefan Agner <stefan@...er.ch>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-pm@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-staging@...ts.linux.dev, linux-spi@...r.kernel.org,
        linux-pwm@...r.kernel.org, linux-mtd@...ts.infradead.org,
        linux-mmc@...r.kernel.org, linux-media@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-clk@...r.kernel.org
Subject: Re: [PATCH v8 20/34] mmc: sdhci-tegra: Add runtime PM and OPP support

On Fri, Aug 20, 2021 at 01:37:13AM +0300, Dmitry Osipenko wrote:
> 19.08.2021 20:03, Thierry Reding пишет:
> > On Tue, Aug 17, 2021 at 04:27:40AM +0300, Dmitry Osipenko wrote:
> >> The SDHCI on Tegra belongs to the core power domain and we're going to
> >> enable GENPD support for the core domain. Now SDHCI must be resumed using
> >> runtime PM API in order to initialize the SDHCI power state. The SDHCI
> >> clock rate must be changed using OPP API that will reconfigure the power
> >> domain performance state in accordance to the rate. Add runtime PM and OPP
> >> support to the SDHCI driver.
> >>
> >> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> >> ---
> >>  drivers/mmc/host/sdhci-tegra.c | 146 ++++++++++++++++++++++++---------
> >>  1 file changed, 105 insertions(+), 41 deletions(-)
> >>
> >> diff --git a/drivers/mmc/host/sdhci-tegra.c b/drivers/mmc/host/sdhci-tegra.c
> >> index 387ce9cdbd7c..a3583359c972 100644
> >> --- a/drivers/mmc/host/sdhci-tegra.c
> >> +++ b/drivers/mmc/host/sdhci-tegra.c
> >> @@ -15,6 +15,8 @@
> >>  #include <linux/of.h>
> >>  #include <linux/of_device.h>
> >>  #include <linux/pinctrl/consumer.h>
> >> +#include <linux/pm_opp.h>
> >> +#include <linux/pm_runtime.h>
> >>  #include <linux/regulator/consumer.h>
> >>  #include <linux/reset.h>
> >>  #include <linux/mmc/card.h>
> >> @@ -24,6 +26,8 @@
> >>  #include <linux/gpio/consumer.h>
> >>  #include <linux/ktime.h>
> >>  
> >> +#include <soc/tegra/common.h>
> >> +
> >>  #include "sdhci-pltfm.h"
> >>  #include "cqhci.h"
> >>  
> >> @@ -123,6 +127,12 @@
> >>  					 SDHCI_TRNS_BLK_CNT_EN | \
> >>  					 SDHCI_TRNS_DMA)
> >>  
> >> +enum {
> >> +	TEGRA_CLK_BULK_SDHCI,
> >> +	TEGRA_CLK_BULK_TMCLK,
> >> +	TEGRA_CLK_BULK_NUM,
> >> +};
> >> +
> >>  struct sdhci_tegra_soc_data {
> >>  	const struct sdhci_pltfm_data *pdata;
> >>  	u64 dma_mask;
> >> @@ -171,6 +181,8 @@ struct sdhci_tegra {
> >>  	bool enable_hwcq;
> >>  	unsigned long curr_clk_rate;
> >>  	u8 tuned_tap_delay;
> >> +
> >> +	struct clk_bulk_data clocks[TEGRA_CLK_BULK_NUM];
> > 
> > This doesn't seem worth it to me. There's a lot of churn in this driver
> > that's only needed to convert this to the clk_bulk API and it makes the
> > code a lot more difficult to read, in my opinion.
> > 
> > It looks like the only benefit that this gives us is that runtime
> > suspend and resume become a few lines shorter.
> 
> The driver probe code looks cleaner with that. You should be looking at
> the final result and not at the patch to see it.

I did look at the final result and didn't find it cleaner at all. =)

Thierry

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