linux-kernel - Re: [PATCH v4 3/5] mmc: sdhci: fix SDHCI_QUIRK2_CLOCK_DIV_ZERO

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Message-ID: <YQ6T1d4VElzQclsX@qmqm.qmqm.pl>
Date:   Sat, 7 Aug 2021 16:08:21 +0200
From:   Michał Mirosław <mirq-linux@...e.qmqm.pl>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Suneel Garapati <suneel.garapati@...inx.com>,
        Kevin Liu <kliu5@...vell.com>,
        Michal Simek <michal.simek@...inx.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-kernel@...r.kernel.org, linux-mmc@...r.kernel.org,
        Al Cooper <alcooperx@...il.com>
Subject: Re: [PATCH v4 3/5] mmc: sdhci: fix SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN

On Wed, Aug 04, 2021 at 02:06:55PM +0300, Adrian Hunter wrote:
> On 25/07/21 12:20 pm, Michał Mirosław wrote:
> > Fix returned clock rate for SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN case.
> > This fixes real_div value that was calculated as 1 (meaning no division)
> > instead of 2 with the quirk enabled.
> > 
> > Cc: stable@...nel.vger.org
> > Fixes: d1955c3a9a1d ("mmc: sdhci: add quirk SDHCI_QUIRK_CLOCK_DIV_ZERO_BROKEN")
> > Signed-off-by: Michał Mirosław <mirq-linux@...e.qmqm.pl>
> 
> Notwithstanding comment below:
> 
> Acked-by: Adrian Hunter <adrian.hunter@...el.com>
[...]
> > --- a/drivers/mmc/host/sdhci.c
> > +++ b/drivers/mmc/host/sdhci.c
> > @@ -1903,9 +1903,12 @@ u16 sdhci_calc_clk(struct sdhci_host *host, unsigned int clock,
> >  
> >  		if (!host->clk_mul || switch_base_clk) {
> >  			/* Version 3.00 divisors must be a multiple of 2. */
> > -			if (host->max_clk <= clock)
> > +			if (host->max_clk <= clock) {
> >  				div = 1;
> > -			else {
> > +				if ((host->quirks2 & SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN)
> > +					&& host->max_clk <= 25000000)
> 
> It is preferred to line break after '&&' and line up e.g.
> 
> 				if ((host->quirks2 & SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN) &&
> 				    host->max_clk <= 25000000)

This was just old code moved, but fixed for next version.

> 
> 
> > +					div = 2;
> > +			} else {
> >  				for (div = 2; div < SDHCI_MAX_DIV_SPEC_300;
> >  				     div += 2) {
> >  					if ((host->max_clk / div) <= clock)
> > @@ -1914,9 +1917,6 @@ u16 sdhci_calc_clk(struct sdhci_host *host, unsigned int clock,
> >  			}
> >  			real_div = div;
> >  			div >>= 1;
> > -			if ((host->quirks2 & SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN)
> > -				&& !div && host->max_clk <= 25000000)
> > -				div = 1;
> >  		}
> >  	} else {
> >  		/* Version 2.00 divisors must be a power of 2. */
> > 
>