[PATCH] pinctrl: pinctrl-single: Avoid divisions in context save/restore

[PATCH] pinctrl: pinctrl-single: Avoid divisions in context save/restore

[Geert Uytterhoeven]

The divisions (and multiplications) can be avoided by changing the loops
to use increments of mux_bytes instead of 1.
While at it, remove the unneeded casts when assigning void pointers.

This saves +100 bytes of kernel size on arm32/arm64.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
Compile-tested only.

As the loops are now identical, the code could be made even smaller by
moving the switch() inside the loop, at the expense of readability.
---
 drivers/pinctrl/pinctrl-single.c | 36 ++++++++++++++++++------------------
 1 file changed, 18 insertions(+), 18 deletions(-)

diff --git a/drivers/pinctrl/pinctrl-single.c b/drivers/pinctrl/pinctrl-single.c
index 9c3c00515aa0fe20..5de5dedb804928eb 100644
--- a/drivers/pinctrl/pinctrl-single.c
+++ b/drivers/pinctrl/pinctrl-single.c
@@ -1593,19 +1593,19 @@ static int pcs_save_context(struct pcs_device *pcs)
 
 	switch (pcs->width) {
 	case 64:
-		regsl = (u64 *)pcs->saved_vals;
-		for (i = 0; i < pcs->size / mux_bytes; i++)
-			regsl[i] = pcs->read(pcs->base + i * mux_bytes);
+		regsl = pcs->saved_vals;
+		for (i = 0; i < pcs->size; i += mux_bytes)
+			*regsl++ = pcs->read(pcs->base + i);
 		break;
 	case 32:
-		regsw = (u32 *)pcs->saved_vals;
-		for (i = 0; i < pcs->size / mux_bytes; i++)
-			regsw[i] = pcs->read(pcs->base + i * mux_bytes);
+		regsw = pcs->saved_vals;
+		for (i = 0; i < pcs->size; i += mux_bytes)
+			*regsw++ = pcs->read(pcs->base + i);
 		break;
 	case 16:
-		regshw = (u16 *)pcs->saved_vals;
-		for (i = 0; i < pcs->size / mux_bytes; i++)
-			regshw[i] = pcs->read(pcs->base + i * mux_bytes);
+		regshw = pcs->saved_vals;
+		for (i = 0; i < pcs->size; i += mux_bytes)
+			*regshw++ = pcs->read(pcs->base + i);
 		break;
 	}
 
@@ -1623,19 +1623,19 @@ static void pcs_restore_context(struct pcs_device *pcs)
 
 	switch (pcs->width) {
 	case 64:
-		regsl = (u64 *)pcs->saved_vals;
-		for (i = 0; i < pcs->size / mux_bytes; i++)
-			pcs->write(regsl[i], pcs->base + i * mux_bytes);
+		regsl = pcs->saved_vals;
+		for (i = 0; i < pcs->size; i += mux_bytes)
+			pcs->write(*regsl++, pcs->base + i);
 		break;
 	case 32:
-		regsw = (u32 *)pcs->saved_vals;
-		for (i = 0; i < pcs->size / mux_bytes; i++)
-			pcs->write(regsw[i], pcs->base + i * mux_bytes);
+		regsw = pcs->saved_vals;
+		for (i = 0; i < pcs->size; i += mux_bytes)
+			pcs->write(*regsw++, pcs->base + i);
 		break;
 	case 16:
-		regshw = (u16 *)pcs->saved_vals;
-		for (i = 0; i < pcs->size / mux_bytes; i++)
-			pcs->write(regshw[i], pcs->base + i * mux_bytes);
+		regshw = pcs->saved_vals;
+		for (i = 0; i < pcs->size; i += mux_bytes)
+			pcs->write(*regshw++, pcs->base + i);
 		break;
 	}
 }
-- 
2.7.4

Re: [PATCH] pinctrl: pinctrl-single: Avoid divisions in context save/restore

[Tony Lindgren]

* Geert Uytterhoeven <geert+renesas@glider.be> [180607 13:40]:
> The divisions (and multiplications) can be avoided by changing the loops
> to use increments of mux_bytes instead of 1.
> While at it, remove the unneeded casts when assigning void pointers.
> 
> This saves +100 bytes of kernel size on arm32/arm64.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
> Compile-tested only.

Makes sense to me:

Acked-by: Tony Lindgren <tony@atomide.com>

Keerthy can you please test?

Regards,

Tony

Re: [PATCH] pinctrl: pinctrl-single: Avoid divisions in context save/restore

[Keerthy]

On Friday 08 June 2018 11:56 AM, Tony Lindgren wrote:
> * Geert Uytterhoeven <geert+renesas@glider.be> [180607 13:40]:
>> The divisions (and multiplications) can be avoided by changing the loops
>> to use increments of mux_bytes instead of 1.
>> While at it, remove the unneeded casts when assigning void pointers.
>>
>> This saves +100 bytes of kernel size on arm32/arm64.
>>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
>> ---
>> Compile-tested only.
> 
> Makes sense to me:
> 
> Acked-by: Tony Lindgren <tony@atomide.com>
> 
> Keerthy can you please test?

Tested on AM437x-gp-evm for Deep Sleep0.

Tested-by: Keerthy <j-keerthy@ti.com>
Reviewed-by: Keerthy <j-keerthy@ti.com>

Thanks Geert!

> 
> Regards,
> 
> Tony
> 

Re: [PATCH] pinctrl: pinctrl-single: Avoid divisions in context save/restore

[Linus Walleij]

On Thu, Jun 7, 2018 at 2:24 PM, Geert Uytterhoeven
<geert+renesas@glider.be> wrote:

> The divisions (and multiplications) can be avoided by changing the loops
> to use increments of mux_bytes instead of 1.
> While at it, remove the unneeded casts when assigning void pointers.
>
> This saves +100 bytes of kernel size on arm32/arm64.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>

Patch applied for v4.19.

Yours,
Linus Walleij