Re: [PATCH] sh-pfc: handle pin array holes in sh_pfc_map_pins()

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Hello.

On 03/03/2015 03:24 AM, Laurent Pinchart wrote:

Sorry for the belated reply, I was switched to EtherAVB soon after posting this patch. :-)

The  pin array handled by sh_pfc_map_pins() may contain holes representing
non- existing pins. We have to first count the valid pins in order to
calculate the size  of the memory to be allocated, then to skip over the
non-existing pins when  initializing the allocated arrays, and then to
return the number of valid pins  from sh_pfc_map_pins() instead of 0 on
success.

As we have to touch devm_kzalloc() calls anyway, use more fitting
devm_kcalloc() instead which additionally checks the array size. And since
PINMUX_TYPE_NONE is #define'd as 0, stop re-initializing already zeroed out
'pmx->configs' array.

I agree with this optimization, but I think it deserves a comment in the
source code that explicitly mentions PINMUX_TYPE_NONE, to make sure any later
rework changing the PINMUX_TYPE_NONE value would catch this.

   OK, will do.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@xxxxxxxxxxxxxxxxxx>

---
The patch is against the 'devel' branch of Linus W.'s 'linux-pinctrl.git'
repo. This patch should be applied before my R8A7794 PFC support patch and
before Laurent's patches removing non-existent GPIOs for R8A779[01],
otherwise they would cause the kernel  to hang while booting!

  drivers/pinctrl/sh-pfc/pinctrl.c |   32 +++++++++++++++++++-------------
  1 file changed, 19 insertions(+), 13 deletions(-)

Index: linux-pinctrl/drivers/pinctrl/sh-pfc/pinctrl.c
===================================================================
--- linux-pinctrl.orig/drivers/pinctrl/sh-pfc/pinctrl.c
+++ linux-pinctrl/drivers/pinctrl/sh-pfc/pinctrl.c
@@ -571,33 +571,39 @@ static const struct pinconf_ops sh_pfc_p
  /* PFC ranges -> pinctrl pin descs */
  static int sh_pfc_map_pins(struct sh_pfc *pfc, struct sh_pfc_pinctrl *pmx)
  {
-	unsigned int i;
+	const struct sh_pfc_pin *info;
+	struct pinctrl_pin_desc *pin;
+	unsigned int i, n;

Could you please rename n to num_pins, and declare it on its own line to match
the coding style of the file ?

   Will do.

+
+	/* Count the valid pins. */
+	for (i = 0, info = pfc->info->pins, n = 0;
+	     i < pfc->info->nr_pins; i++, info++) {
+		if (info->enum_id || info->configs)

Why do you need to test info->configs as well ? I thought enum_id == 0 is
always reserved, am I getting it wrong ?

   Look at SH_PFC_PIN_NAMED() and its users.

+			n++;
+	}

  	/* Allocate and initialize the pins and configs arrays. */
-	pmx->pins = devm_kzalloc(pfc->dev,
-				 sizeof(*pmx->pins) * pfc->info->nr_pins,
-				 GFP_KERNEL);
+	pmx->pins = devm_kcalloc(pfc->dev, n, sizeof(*pmx->pins), GFP_KERNEL);
  	if (unlikely(!pmx->pins))
  		return -ENOMEM;

-	pmx->configs = devm_kzalloc(pfc->dev,
-				    sizeof(*pmx->configs) * pfc->info->nr_pins,
+	pmx->configs = devm_kcalloc(pfc->dev, n, sizeof(*pmx->configs),
  				    GFP_KERNEL);
  	if (unlikely(!pmx->configs))
  		return -ENOMEM;

-	for (i = 0; i < pfc->info->nr_pins; ++i) {
-		const struct sh_pfc_pin *info = &pfc->info->pins[i];
-		struct sh_pfc_pin_config *cfg = &pmx->configs[i];
-		struct pinctrl_pin_desc *pin = &pmx->pins[i];
+	for (i = 0, info = pfc->info->pins, pin = pmx->pins;
+	     i < pfc->info->nr_pins; i++, info++) {

I would keep info as a local variable to avoid splitting the for () on
multiple lines. Same comment for the counter loop above.

I don't want to declare the same variable twice, so prefer doing gcc's work of optimizing loop induction variable myself in this case. If you insist, this can be changed...

[...]
@@ -622,7 +628,7 @@ int sh_pfc_register_pinctrl(struct sh_pf
  	pmx->pctl_desc.pmxops = &sh_pfc_pinmux_ops;
  	pmx->pctl_desc.confops = &sh_pfc_pinconf_ops;
  	pmx->pctl_desc.pins = pmx->pins;
-	pmx->pctl_desc.npins = pfc->info->nr_pins;
+	pmx->pctl_desc.npins = ret;

  	pmx->pctl = pinctrl_register(&pmx->pctl_desc, pfc->dev, pmx);
  	if (pmx->pctl == NULL)

Shouldn't you also fix sh_pfc_init_ranges() ? It includes the following code
that doesn't seem to handle holes properly.

         for (i = 1, nr_ranges = 1; i < pfc->info->nr_pins; ++i) {
                 if (pfc->info->pins[i-1].pin != pfc->info->pins[i].pin - 1)
                         nr_ranges++;
         }

   Sorry, missed it, will try to deal with this as well...

Please make sure that sh_pfc_get_pin_index() doesn't start blowing up
afterwards though.

   Will do.

WBR, Sergei

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