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

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Message-ID: <8c03b995-f449-8f12-a4cf-8fc4978f05c7@intel.com>
Date:   Wed, 4 Aug 2021 14:06:55 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Suneel Garapati <suneel.garapati@...inx.com>,
        Kevin Liu <kliu5@...vell.com>,
        Michal Simek <michal.simek@...inx.com>,
        Ulf Hansson <ulf.hansson@...aro.org>
Cc:     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 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>


> ---
> v4: no changes
> v3: updated commit message
> v2: no changes
> ---
>  drivers/mmc/host/sdhci.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 3ab60e7f936b..0993f7d0ce8e 100644
> --- 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)


> +					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. */
>