linux-kernel - Re: [LINUX PATCH 1/5] mmc: Workaround for the issue in auto tuning mode.

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Message-ID: <20160119175757.GR19062@n2100.arm.linux.org.uk>
Date:	Tue, 19 Jan 2016 17:57:58 +0000
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	P L Sai Krishna <lakshmi.sai.krishna.potthuri@...inx.com>
Cc:	Michal Simek <michal.simek@...inx.com>,
	Soren Brinkmann <soren.brinkmann@...inx.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Kevin Hao <haokexin@...il.com>,
	Emil Lenchak <emill@...inx.com>,
	Tobias Klauser <tklauser@...tanz.ch>,
	Sudeep Holla <Sudeep.Holla@....com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Jisheng Zhang <jszhang@...vell.com>,
	"Ivan T. Ivanov" <ivan.ivanov@...aro.org>,
	Scott Branden <sbranden@...adcom.com>,
	Vincent Yang <vincent.yang.fujitsu@...il.com>,
	Haibo Chen <haibo.chen@...escale.com>,
	Marek Vasut <marex@...x.de>,
	"ludovic.desroches@...el.com" <ludovic.desroches@...el.com>,
	Rob Herring <robh+dt@...nel.org>,
	Pawel Moll <pawel.moll@....com>,
	Mark Rutland <mark.rutland@....com>,
	Ian Campbell <ijc+devicetree@...lion.org.uk>,
	Kumar Gala <galak@...eaurora.org>,
	Suman Tripathi <stripathi@....com>,
	Shawn Lin <shawn.lin@...k-chips.com>,
	devicetree@...r.kernel.org, Harini Katakam <harinik@...inx.com>,
	linux-mmc@...r.kernel.org, linux-kernel@...r.kernel.org,
	P L Sai Krishna <lakshmis@...inx.com>,
	Anirudha Sarangi <anirudh@...inx.com>,
	Punnaiah Choudary Kalluri <punnaia@...inx.com>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [LINUX PATCH 1/5] mmc: Workaround for the issue in auto tuning
 mode.

On Tue, Jan 19, 2016 at 07:47:31PM +0530, P L Sai Krishna wrote:
> +void arasan_tune_sdclk(struct sdhci_host *host)

static?

> +{
> +	unsigned int clock;
> +
> +	clock = host->clock;

Maybe combine the above two lines:

	unsigned int clock = host->clock;

?

> +
> +	/*
> +	 * As per controller erratum, program the SDCLK Frequency
> +	 * Select of clock control register with a value, say
> +	 * clock/2. Wait for the Internal clock stable and program
> +	 * the desired frequency.
> +	 */
> +	host->ops->set_clock(host, clock/2);

The comment above says "wait for the internal clock stable" - I see
no wait in here.  Does the code actually conform with the comment?

Please also use "clock / 2" as per coding style, thanks

> +
> +	host->ops->set_clock(host, host->clock);

Maybe replace host->clock with clock?

> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index d622435..8b064cd 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2043,6 +2043,11 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
>  		err = -EIO;
>  	}
>  
> +	if ((host->quirks2 & SDHCI_QUIRK2_BROKEN_TUNING) &&
> +		(tuning_loop_counter >= 0) && (ctrl & SDHCI_CTRL_TUNED_CLK)) {
> +		host->ops->tune_clk(host);
> +	}

Do we need this "SDHCI_QUIRK2_BROKEN_TUNING" quirk at all?  What's wrong
with:

	if (host->ops->tune_clk && tuning_loop_counter >= 0 &&
	    ctrl & SDHCI_CTRL_TUNED_CLK)
		host->ops->tune_clk(host);

here?

-- 
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