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

Lakshmi Sai Krishna Potthuri
2016-01-20T06:02:12Z

Hi,

> -----Original Message-----
> From: Russell King - ARM Linux [mailto:linux at arm.linux.org.uk]
> Sent: Tuesday, January 19, 2016 11:28 PM
> To: Lakshmi Sai Krishna Potthuri
> Cc: Michal Simek; Soren Brinkmann; Ulf Hansson; Kevin Hao; Emil P. Lenchak;
> Tobias Klauser; Sudeep Holla; Adrian Hunter; Jisheng Zhang; Ivan T. Ivanov;
> Scott Branden; Vincent Yang; Haibo Chen; Marek Vasut;
> ludovic.desroches at atmel.com; Rob Herring; Pawel Moll; Mark Rutland; Ian
> Campbell; Kumar Gala; Suman Tripathi; Shawn Lin;
> devicetree at vger.kernel.org; Harini Katakam; linux-mmc at vger.kernel.org;
> linux-kernel at vger.kernel.org; Lakshmi Sai Krishna Potthuri; Anirudha
> Sarangi; Punnaiah Choudary Kalluri; linux-arm-kernel at lists.infradead.org
> Subject: Re: [LINUX PATCH 1/5] mmc: Workaround for the issue in auto
> tuning mode.
>
<snip>
> > +
> > + /*
> > + * 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?

Wait for internal clock stable is taken care of inside
set_clock()

<snip>
> > + 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?
>

tune_clock is provided as part of ops and will always be present.
Other users of arasan and this driver might not have tuning broken
And won't use this manual tuning.

Regards
Sai Krishna

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