[PATCH] mmc: sdhi: fill in actual_clock

[PATCH] mmc: sdhi: fill in actual_clock

[Tamás Szűcs]

Save set clock in mmc_host actual_clock enabling exporting it via debugfs.
This will indicate the precise SD clock in I/O settings rather than only the
sometimes misleading requested clock.

Signed-off-by: Tamás Szűcs <tszucs@protonmail.ch>
---
 drivers/mmc/host/renesas_sdhi_core.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/mmc/host/renesas_sdhi_core.c b/drivers/mmc/host/renesas_sdhi_core.c
index 64d3b5fb7fe5..ae842d0b59f9 100644
--- a/drivers/mmc/host/renesas_sdhi_core.c
+++ b/drivers/mmc/host/renesas_sdhi_core.c
@@ -124,7 +124,7 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host,
 {
 	struct renesas_sdhi *priv = host_to_priv(host);
 	unsigned int freq, diff, best_freq = 0, diff_min = ~0;
-	int i, ret;
+	int i;
 
 	/* tested only on R-Car Gen2+ currently; may work for others */
 	if (!(host->pdata->flags & TMIO_MMC_MIN_RCAR2))
@@ -153,9 +153,11 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host,
 		}
 	}
 
-	ret = clk_set_rate(priv->clk, best_freq);
+	host->mmc->actual_clock =
+		clk_set_rate(priv->clk, best_freq) == 0 ?
+			best_freq : clk_get_rate(priv->clk);
 
-	return ret == 0 ? best_freq : clk_get_rate(priv->clk);
+	return host->mmc->actual_clock;
 }
 
 static void renesas_sdhi_set_clock(struct tmio_mmc_host *host,
-- 
2.11.0

Re: [PATCH] mmc: sdhi: fill in actual_clock

[Geert Uytterhoeven]

Hi Tamás,

On Wed, Aug 28, 2019 at 9:02 PM Tamás Szűcs <tszucs@protonmail.ch> wrote:
> Save set clock in mmc_host actual_clock enabling exporting it via debugfs.
> This will indicate the precise SD clock in I/O settings rather than only the
> sometimes misleading requested clock.
>
> Signed-off-by: Tamás Szűcs <tszucs@protonmail.ch>

Thanks for your patch!

> --- a/drivers/mmc/host/renesas_sdhi_core.c
> +++ b/drivers/mmc/host/renesas_sdhi_core.c
> @@ -124,7 +124,7 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host,
>  {
>         struct renesas_sdhi *priv = host_to_priv(host);
>         unsigned int freq, diff, best_freq = 0, diff_min = ~0;
> -       int i, ret;
> +       int i;
>
>         /* tested only on R-Car Gen2+ currently; may work for others */
>         if (!(host->pdata->flags & TMIO_MMC_MIN_RCAR2))
> @@ -153,9 +153,11 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host,
>                 }
>         }
>
> -       ret = clk_set_rate(priv->clk, best_freq);
> +       host->mmc->actual_clock =
> +               clk_set_rate(priv->clk, best_freq) == 0 ?
> +                       best_freq : clk_get_rate(priv->clk);

When clk_set_rate() returns 0 to indicate success, it may still have
rounded the requested clock rate, no?
So wouldn't it be better to always call clk_get_rate()?
>
> -       return ret == 0 ? best_freq : clk_get_rate(priv->clk);
> +       return host->mmc->actual_clock;
>  }

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

Re: [PATCH] mmc: sdhi: fill in actual_clock

[Tamás Szűcs]

Hi Geert,

It would be possible to call clk_get_rate() unconditionally but there's usually no need, thus the ternary. Are you in favor of that though?

It turns out I need to send a followup to fix some glitches. Please stay tuned.

Kind regards,
Tamas


Tamás Szűcs
tszucs@protonmail.ch

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Thursday, August 29, 2019 9:47 AM, Geert Uytterhoeven <geert@linux-m68k.org> wrote:

> Hi Tamás,
>
> On Wed, Aug 28, 2019 at 9:02 PM Tamás Szűcs tszucs@protonmail.ch wrote:
>
> > Save set clock in mmc_host actual_clock enabling exporting it via debugfs.
> > This will indicate the precise SD clock in I/O settings rather than only the
> > sometimes misleading requested clock.
> > Signed-off-by: Tamás Szűcs tszucs@protonmail.ch
>
> Thanks for your patch!
>
> > --- a/drivers/mmc/host/renesas_sdhi_core.c
> > +++ b/drivers/mmc/host/renesas_sdhi_core.c
> > @@ -124,7 +124,7 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host,
> > {
> > struct renesas_sdhi *priv = host_to_priv(host);
> > unsigned int freq, diff, best_freq = 0, diff_min = ~0;
> >
> > -         int i, ret;
> >
> >
> >
> > -         int i;
> >
> >           /* tested only on R-Car Gen2+ currently; may work for others */
> >           if (!(host->pdata->flags & TMIO_MMC_MIN_RCAR2))
> >
> >
> >
> > @@ -153,9 +153,11 @@ static unsigned int renesas_sdhi_clk_update(struct tmio_mmc_host *host,
> > }
> > }
> >
> > -         ret = clk_set_rate(priv->clk, best_freq);
> >
> >
> >
> > -         host->mmc->actual_clock =
> >
> >
> > -                 clk_set_rate(priv->clk, best_freq) == 0 ?
> >
> >
> > -                         best_freq : clk_get_rate(priv->clk);
> >
> >
>
> When clk_set_rate() returns 0 to indicate success, it may still have
> rounded the requested clock rate, no?
> So wouldn't it be better to always call clk_get_rate()?
>
> > -         return ret == 0 ? best_freq : clk_get_rate(priv->clk);
> >
> >
> >
> > -         return host->mmc->actual_clock;
> >
> >
> >
> > }
>
> Gr{oetje,eeting}s,
>
> Geert
>
> ----------------------------
>
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds

Re: [PATCH] mmc: sdhi: fill in actual_clock

[Wolfram Sang]

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> It would be possible to call clk_get_rate() unconditionally but
> there's usually no need, thus the ternary. Are you in favor of that
> though?

I like Geert's suggestion. Even if it is "usually" not needed, I think
it is better to be always proper. This is not a hot code path.


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