Re: [PATCH] mmc: sdhci: Fix SDHCI_QUIRK_TIMEOUT_USES_SDCLK

[Andrei Warkentin <andreiw@motorola.com>]

On Tue, Apr 19, 2011 at 12:44 PM, Mark Brown
<broonie@opensource.wolfsonmicro.com> wrote:
> Commit 373e6a (mmc: sdhci: R1B command handling + MMC_CAP_ERASE) moved the
> handling of SDHCI_QUIRK_TIMEOUT_USES_SDCLK from sdhci_calc_timeout() to
> sdhci_add_host(). This causes division by zero errors on at least the S3C
> SDHCI controller as the quirk implementation needs host->clock set to work
> but host->clock has not been set when sdhci_add_host() is called.
>
> Fix this by backing out that portion of the change, the clock may vary at
> runtime anyway. It does occur to me that we may want to move the quirk to
> where we set the clock but this seems more invasive and I'm concerned
> about undesirable side effects.
>
> Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
> ---
>  drivers/mmc/host/sdhci.c |    7 ++++---
>  1 files changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index f79dead..da57bdb 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -616,6 +616,9 @@ static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd)
>                target_timeout = data->timeout_ns / 1000 +
>                        data->timeout_clks / host->clock;
>
> +       if (host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)
> +               host->timeout_clk = host->clock / 1000;
> +
>        /*
>         * Figure out needed cycles.
>         * We do this in steps in order to fit inside a 32 bit int.
> @@ -626,6 +629,7 @@ static u8 sdhci_calc_timeout(struct sdhci_host *host, struct mmc_command *cmd)
>         *     =>
>         *     (1) / (2) > 2^6
>         */
> +       BUG_ON(!host->timeout_clk);
>        count = 0;
>        current_timeout = (1 << 13) * 1000 / host->timeout_clk;
>        while (current_timeout < target_timeout) {
> @@ -1894,9 +1898,6 @@ int sdhci_add_host(struct sdhci_host *host)
>        if (caps & SDHCI_TIMEOUT_CLK_UNIT)
>                host->timeout_clk *= 1000;
>
> -       if (host->quirks & SDHCI_QUIRK_DATA_TIMEOUT_USES_SDCLK)
> -               host->timeout_clk = host->clock / 1000;
> -
>        /*
>         * Set host parameters.
>         */
> --
> 1.7.4.1
>
>

Sorry about that. I thought I had the right idea.

I'll try to be more careful.

A