[1/2] pinctrl: sunxi: Increase size of regulator array
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Message ID 20190110082633.6321-1-wens@csie.org
State New
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  • [1/2] pinctrl: sunxi: Increase size of regulator array
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Commit Message

Chen-Yu Tsai Jan. 10, 2019, 8:26 a.m. UTC
On the A80, the pin banks go up to PN, which translates to the 14th
entry in the regulator array. The array is only 12 entries long, which
causes the sunxi_pmx_{request,free} functions to access beyond the
array on the A80 and the A31 (which has pin bank PM). While the
accessed data is still valid allocated data within the same driver
data structure, it is likely not a pointer.

Increase the size of the regulator array from 12 to 14. This is a simple
fix. While we could have the code take into account the fact that R_PIO
pin banks start from PL, or maybe even dynamically allocate the array
based on the last pin of the pin controller, the size reduction probably
isn't worth the additional code complexity.

Fixes: 9a2a566adb00 ("pinctrl: sunxi: Deal with per-bank regulators")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
---
This fixes a crash due to an invalid pointer on the A80.
---
 drivers/pinctrl/sunxi/pinctrl-sunxi.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Maxime Ripard Jan. 10, 2019, 3:26 p.m. UTC | #1
Hi,

On Thu, Jan 10, 2019 at 04:26:32PM +0800, Chen-Yu Tsai wrote:
> On the A80, the pin banks go up to PN, which translates to the 14th
> entry in the regulator array. The array is only 12 entries long, which
> causes the sunxi_pmx_{request,free} functions to access beyond the
> array on the A80 and the A31 (which has pin bank PM). While the
> accessed data is still valid allocated data within the same driver
> data structure, it is likely not a pointer.
> 
> Increase the size of the regulator array from 12 to 14. This is a simple
> fix. While we could have the code take into account the fact that R_PIO
> pin banks start from PL, or maybe even dynamically allocate the array
> based on the last pin of the pin controller, the size reduction probably
> isn't worth the additional code complexity.
> 
> Fixes: 9a2a566adb00 ("pinctrl: sunxi: Deal with per-bank regulators")
> Signed-off-by: Chen-Yu Tsai <wens@csie.org>

I definitely overlooked the R_PIO case, sorry. I guess the proper fix
would be the first alternative one you suggested, and we should take
the pin_base into account. There's no need to store twice such a large
array for this case.

Maxime
Chen-Yu Tsai Jan. 11, 2019, 1:46 p.m. UTC | #2
On Thu, Jan 10, 2019 at 11:26 PM Maxime Ripard
<maxime.ripard@bootlin.com> wrote:
>
> Hi,
>
> On Thu, Jan 10, 2019 at 04:26:32PM +0800, Chen-Yu Tsai wrote:
> > On the A80, the pin banks go up to PN, which translates to the 14th
> > entry in the regulator array. The array is only 12 entries long, which
> > causes the sunxi_pmx_{request,free} functions to access beyond the
> > array on the A80 and the A31 (which has pin bank PM). While the
> > accessed data is still valid allocated data within the same driver
> > data structure, it is likely not a pointer.
> >
> > Increase the size of the regulator array from 12 to 14. This is a simple
> > fix. While we could have the code take into account the fact that R_PIO
> > pin banks start from PL, or maybe even dynamically allocate the array
> > based on the last pin of the pin controller, the size reduction probably
> > isn't worth the additional code complexity.
> >
> > Fixes: 9a2a566adb00 ("pinctrl: sunxi: Deal with per-bank regulators")
> > Signed-off-by: Chen-Yu Tsai <wens@csie.org>
>
> I definitely overlooked the R_PIO case, sorry. I guess the proper fix
> would be the first alternative one you suggested, and we should take
> the pin_base into account. There's no need to store twice such a large
> array for this case.

OK.

I wonder if we should try to get rid of pin_base though, at least as far
as the pinctrl core is concerned. In other words, in our description we'd
still have PL0 == 352, but when the pin is registered, PL0 == 0. This is
OK since each pinctrl device has its own numbering space. And it would
match up with what we use for GPIO.

It would also be better to nail this down one way or the other if we want
to use the gpio-ranges property.

Either way this would be a separate patch.

ChenYu

Patch
diff mbox series

diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.h b/drivers/pinctrl/sunxi/pinctrl-sunxi.h
index e340d2a24b44..e8161aa17dab 100644
--- a/drivers/pinctrl/sunxi/pinctrl-sunxi.h
+++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.h
@@ -136,7 +136,7 @@  struct sunxi_pinctrl {
 	struct gpio_chip		*chip;
 	const struct sunxi_pinctrl_desc	*desc;
 	struct device			*dev;
-	struct sunxi_pinctrl_regulator	regulators[12];
+	struct sunxi_pinctrl_regulator	regulators[14];
 	struct irq_domain		*domain;
 	struct sunxi_pinctrl_function	*functions;
 	unsigned			nfunctions;