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

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Date:   Thu, 19 Aug 2021 19:03:48 +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 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.

Thierry

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