linux-kernel - Re: [PATCH 4/5] mmc: sdhci-omap: Add OMAP SDHCI driver

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Message-ID: <dfe1b4e2-bcb5-c969-efe6-7cddd0eb0bf9@intel.com>
Date:   Thu, 31 Aug 2017 16:02:23 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Kishon Vijay Abraham I <kishon@...com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     Rob Herring <robh+dt@...nel.org>, Tony Lindgren <tony@...mide.com>,
        Sekhar Nori <nsekhar@...com>,
        Russell King <linux@...linux.org.uk>,
        Ravikumar Kattekola <rk@...com>, linux-mmc@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH 4/5] mmc: sdhci-omap: Add OMAP SDHCI driver

On 30/08/17 16:53, Kishon Vijay Abraham I wrote:
> On Monday 28 August 2017 02:36 PM, Adrian Hunter wrote:
>> On 21/08/17 10:41, Kishon Vijay Abraham I wrote:
>>> +
>>> +static void sdhci_omap_set_clock(struct sdhci_host *host, unsigned int clock)
>>> +{
>>> +	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
>>> +	struct sdhci_omap_host *omap_host = sdhci_pltfm_priv(pltfm_host);
>>> +	unsigned long clkdiv;
>>> +
>>> +	if (!clock)
>>> +		return;
>>
>> Are you sure you don't want to stop the clock.
> 
> There is never a case where the MMC core sends a request to stop the clock.
> Maybe this check is not required at all.

It does when voltage switching e.g. mmc_set_uhs_voltage(), but host drivers
should support the possibility anyway.