linux-kernel - Re: [PATCH 1/2] mmc: sdhci: Add PLL Enable support to internal clock setup

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Date:   Thu, 25 Jul 2019 13:21:34 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     "Michael K. Johnson" <johnsonm@...lj.org>
Cc:     Ben Chuang <ben.chuang@...esyslogic.com.tw>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>
Subject: Re: [PATCH 1/2] mmc: sdhci: Add PLL Enable support to internal clock setup

On Thu, 25 Jul 2019 at 13:15, Michael K. Johnson <johnsonm@...lj.org> wrote:
>
> (Working around Ben's SMTP server noise, responding on his behalf...)
>
> On Wed, Jul 24, 2019 at 09:19:30AM +0200, Ulf Hansson wrote:
> > This looks like it could be changed to an usleep_range(), perhaps an
> > additional change on top?
> ...
> > Ditto.
>
> In both cases yes, changed.
>
> > > +       mdelay(1);
> >
> > This is new, maybe add a comment and change to usleep_range().
>
> Entirely removed.
>
> New patch attached for any further review, I can re-send the patchset
> properly without the notice for merge when you're happy with it.

I need an ack from Adrian, but it's probably best to resend anyway.

Kind regards
Uffe

>
>
> The GL9750 and GL9755 chipsets, and possibly others, require PLL Enable
> setup as part of the internal clock setup as described in 3.2.1 Internal
> Clock Setup Sequence of SD Host Controller Simplified Specification
> Version 4.20.  This changes the timeouts to the new specification of
> 150ms for each step and is documented as safe for "prior versions which
> do not support PLL Enable."
>
> Signed-off-by: Ben Chuang <ben.chuang@...esyslogic.com.tw>
> Co-developed-by: Michael K Johnson <johnsonm@...lj.org>
> Signed-off-by: Michael K Johnson <johnsonm@...lj.org>
>
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 59acf8e3331e..14957578bf2e 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -1636,8 +1636,8 @@ void sdhci_enable_clk(struct sdhci_host *host, u16 clk)
>         clk |= SDHCI_CLOCK_INT_EN;
>         sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
>
> -       /* Wait max 20 ms */
> -       timeout = ktime_add_ms(ktime_get(), 20);
> +       /* Wait max 150 ms */
> +       timeout = ktime_add_ms(ktime_get(), 150);
>         while (1) {
>                 bool timedout = ktime_after(ktime_get(), timeout);
>
> @@ -1650,7 +1650,28 @@ void sdhci_enable_clk(struct sdhci_host *host, u16 clk)
>                         sdhci_dumpregs(host);
>                         return;
>                 }
> -               udelay(10);
> +               usleep_range(10,15);
> +       }
> +
> +       clk |= SDHCI_CLOCK_PLL_EN;
> +       clk &= ~SDHCI_CLOCK_INT_STABLE;
> +       sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
> +
> +       /* Wait max 150 ms */
> +       timeout = ktime_add_ms(ktime_get(), 150);
> +       while (1) {
> +               bool timedout = ktime_after(ktime_get(), timeout);
> +
> +               clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
> +               if (clk & SDHCI_CLOCK_INT_STABLE)
> +                       break;
> +               if (timedout) {
> +                       pr_err("%s: PLL clock never stabilised.\n",
> +                              mmc_hostname(host->mmc));
> +                       sdhci_dumpregs(host);
> +                       return;
> +               }
> +               usleep_range(10,15);
>         }
>
>         clk |= SDHCI_CLOCK_CARD_EN;
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index 199712e7adbb..72601a4d2e95 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -114,6 +114,7 @@
>  #define  SDHCI_DIV_HI_MASK     0x300
>  #define  SDHCI_PROG_CLOCK_MODE 0x0020
>  #define  SDHCI_CLOCK_CARD_EN   0x0004
> +#define  SDHCI_CLOCK_PLL_EN    0x0008
>  #define  SDHCI_CLOCK_INT_STABLE        0x0002
>  #define  SDHCI_CLOCK_INT_EN    0x0001
>