[PATCH 0/3] mmc: sh_mmcif: Clock Tweaks

[PATCH 0/3] mmc: sh_mmcif: Clock Tweaks

[Simon Horman]

Hi,

this series of three small patches cleans up the handling
of clocks in the MMCIF driver a little.

Simon Horman (3):
      mmc: sh_mmcif: double clock speed
      mmc: sh_mmcif: mmc->f_max should be half of the bus clock
      mmc: sh_mmcif: Simplify calculation of mmc->f_min

 drivers/mmc/host/sh_mmcif.c |   13 ++++---------
 1 files changed, 4 insertions(+), 9 deletions(-)

[PATCH 1/3] mmc: sh_mmcif: double clock speed

[Simon Horman]

Correct an off-by one error when calculating the clock divisor in cases
where the host clock is a power of two of the target clock.  Previously the
divisor was one greater than the correct value in these cases leading to
the clock being set at half the desired speed.

Thanks to Guennadi Liakhovetski for working with me on
the logic for this change.

Tested-by: Cao Minh Hiep <hiepcm@gmail.com>
Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Simon Horman <horms@verge.net.au>

---
v2
* Rewrite changelog
---
 drivers/mmc/host/sh_mmcif.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c
index 8057bf3..5014bc4 100644
--- a/drivers/mmc/host/sh_mmcif.c
+++ b/drivers/mmc/host/sh_mmcif.c
@@ -453,7 +453,8 @@ static void sh_mmcif_clock_control(struct sh_mmcif_host *host, unsigned int clk)
 		sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_SUP_PCLK);
 	else
 		sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_CLEAR &
-				((fls(host->clk / clk) - 1) << 16));
+				((fls(DIV_ROUND_UP(host->clk,
+						   clk) - 1) - 1) << 16));
 
 	sh_mmcif_bitset(host, MMCIF_CE_CLK_CTRL, CLK_ENABLE);
 }
-- 
1.7.6.3

[PATCH 2/3] mmc: sh_mmcif: mmc->f_max should be half of the bus clock

[Simon Horman]

mmc->f_max should be half of the bus clock.
And now that mmc->f_max is not equal to the bus clock the
latter should be used directly to calculate mmc->f_min.

Cc: Magnus Damm <magnus.damm@gmail.com>
Tested-by: Cao Minh Hiep <hiepcm@gmail.com>
Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Simon Horman <horms@verge.net.au>
---
 drivers/mmc/host/sh_mmcif.c |   12 ++++++------
 1 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c
index 5014bc4..1410baa 100644
--- a/drivers/mmc/host/sh_mmcif.c
+++ b/drivers/mmc/host/sh_mmcif.c
@@ -1297,14 +1297,14 @@ static int __devinit sh_mmcif_probe(struct platform_device *pdev)
 	spin_lock_init(&host->lock);
 
 	mmc->ops = &sh_mmcif_ops;
-	mmc->f_max = host->clk;
+	mmc->f_max = host->clk / 2;
 	/* close to 400KHz */
-	if (mmc->f_max < 51200000)
-		mmc->f_min = mmc->f_max / 128;
-	else if (mmc->f_max < 102400000)
-		mmc->f_min = mmc->f_max / 256;
+	if (host->clk < 51200000)
+		mmc->f_min = host->clk / 128;
+	else if (host->clk < 102400000)
+		mmc->f_min = host->clk / 256;
 	else
-		mmc->f_min = mmc->f_max / 512;
+		mmc->f_min = host->clk / 512;
 	if (pd->ocr)
 		mmc->ocr_avail = pd->ocr;
 	mmc->caps = MMC_CAP_MMC_HIGHSPEED;
-- 
1.7.6.3

[PATCH 3/3] mmc: sh_mmcif: Simplify calculation of mmc->f_min

[Simon Horman]

There is no need to tune mmc->f_min to a value near 400kHz as the MMC core
begins testing frequencies at 400kHz regardless of the value of mmc->f_min.

As suggested by Guennadi Liakhovetski.

Cc: Magnus Damm <magnus.damm@gmail.com>
Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Tested-by: Cao Minh Hiep <hiepcm@gmail.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
---
 drivers/mmc/host/sh_mmcif.c |    8 +-------
 1 files changed, 1 insertions(+), 7 deletions(-)

diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c
index 1410baa..f23b9bd 100644
--- a/drivers/mmc/host/sh_mmcif.c
+++ b/drivers/mmc/host/sh_mmcif.c
@@ -1298,13 +1298,7 @@ static int __devinit sh_mmcif_probe(struct platform_device *pdev)
 
 	mmc->ops = &sh_mmcif_ops;
 	mmc->f_max = host->clk / 2;
-	/* close to 400KHz */
-	if (host->clk < 51200000)
-		mmc->f_min = host->clk / 128;
-	else if (host->clk < 102400000)
-		mmc->f_min = host->clk / 256;
-	else
-		mmc->f_min = host->clk / 512;
+	mmc->f_min = host->clk / 512;
 	if (pd->ocr)
 		mmc->ocr_avail = pd->ocr;
 	mmc->caps = MMC_CAP_MMC_HIGHSPEED;
-- 
1.7.6.3

Re: [PATCH 3/3] mmc: sh_mmcif: Simplify calculation of mmc->f_min

[Guennadi Liakhovetski]

On Wed, 28 Mar 2012, Simon Horman wrote:

> There is no need to tune mmc->f_min to a value near 400kHz as the MMC core
> begins testing frequencies at 400kHz regardless of the value of mmc->f_min.
> 
> As suggested by Guennadi Liakhovetski.
> 
> Cc: Magnus Damm <magnus.damm@gmail.com>
> Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
> Tested-by: Cao Minh Hiep <hiepcm@gmail.com>
> Signed-off-by: Simon Horman <horms@verge.net.au>

Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>

Thanks
Guennadi

> ---
>  drivers/mmc/host/sh_mmcif.c |    8 +-------
>  1 files changed, 1 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/mmc/host/sh_mmcif.c b/drivers/mmc/host/sh_mmcif.c
> index 1410baa..f23b9bd 100644
> --- a/drivers/mmc/host/sh_mmcif.c
> +++ b/drivers/mmc/host/sh_mmcif.c
> @@ -1298,13 +1298,7 @@ static int __devinit sh_mmcif_probe(struct platform_device *pdev)
>  
>  	mmc->ops = &sh_mmcif_ops;
>  	mmc->f_max = host->clk / 2;
> -	/* close to 400KHz */
> -	if (host->clk < 51200000)
> -		mmc->f_min = host->clk / 128;
> -	else if (host->clk < 102400000)
> -		mmc->f_min = host->clk / 256;
> -	else
> -		mmc->f_min = host->clk / 512;
> +	mmc->f_min = host->clk / 512;
>  	if (pd->ocr)
>  		mmc->ocr_avail = pd->ocr;
>  	mmc->caps = MMC_CAP_MMC_HIGHSPEED;
> -- 
> 1.7.6.3
> 

---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/

Re: [PATCH 0/3] mmc: sh_mmcif: Clock Tweaks

[Chris Ball]

Hi,

On Wed, Mar 28 2012, Simon Horman wrote:
> Hi,
>
> this series of three small patches cleans up the handling
> of clocks in the MMCIF driver a little.
>
> Simon Horman (3):
>       mmc: sh_mmcif: double clock speed
>       mmc: sh_mmcif: mmc->f_max should be half of the bus clock
>       mmc: sh_mmcif: Simplify calculation of mmc->f_min

Thanks, pushed all three with Guennadi's ACKs to mmc-next for 3.4.

- Chris.
-- 
Chris Ball   <cjb@laptop.org>   <http://printf.net/>
One Laptop Per Child