[PATCH v2] pinctrl: sunxi: set minimal debounce on input-debounce 0

[PATCH v2] pinctrl: sunxi: set minimal debounce on input-debounce 0

[Andreas Feldner]

sunxi-h3-h5 based boards have no support for switching
off IRQ debouncing filter. This would be the expected
behaviour of value 0 for the general pinctl parameter
input-debounce.
The current driver implementation ignores value 0
for input-debounce, leaving the chip's default. This
default, however, is not minimal, but equivalent to
value 31 (microseconds).

This patch does not ignore value 0 but instead makes
sure the corresponding IRQ debounce filter is set
to the shortest time selectable, i. e. the fast
oscillator with a divider of 1 == (2 ^ 0).

Fixes: 7c926492d38a ("pinctrl: sunxi: Add support for interrupt debouncing")

Signed-off-by: Andreas Feldner <pelzi@flying-snail.de>
---
Changes in v2:
  - Posted as separate mail thread
  - Made sure tabs are kept
  - Excluded patch to devicetree

 drivers/pinctrl/sunxi/pinctrl-sunxi.c | 40 +++++++++++++++------------
 1 file changed, 23 insertions(+), 17 deletions(-)

diff --git a/drivers/pinctrl/sunxi/pinctrl-sunxi.c b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
index f35179eceb4e..6798c8f4067e 100644
--- a/drivers/pinctrl/sunxi/pinctrl-sunxi.c
+++ b/drivers/pinctrl/sunxi/pinctrl-sunxi.c
@@ -1444,29 +1444,35 @@ static int sunxi_pinctrl_setup_debounce(struct sunxi_pinctrl *pctl,
 		if (ret)
 			return ret;
 
-		if (!debounce)
-			continue;
-
-		debounce_freq = DIV_ROUND_CLOSEST(USEC_PER_SEC, debounce);
-		losc_div = sunxi_pinctrl_get_debounce_div(losc,
-							  debounce_freq,
-							  &losc_diff);
-
-		hosc_div = sunxi_pinctrl_get_debounce_div(hosc,
-							  debounce_freq,
-							  &hosc_diff);
-
-		if (hosc_diff < losc_diff) {
-			div = hosc_div;
-			src = 1;
+		if (debounce) {
+			debounce_freq = DIV_ROUND_CLOSEST(USEC_PER_SEC, debounce);
+			losc_div = sunxi_pinctrl_get_debounce_div(losc,
+								  debounce_freq,
+								  &losc_diff);
+
+			hosc_div = sunxi_pinctrl_get_debounce_div(hosc,
+								  debounce_freq,
+								  &hosc_diff);
+
+			if (hosc_diff < losc_diff) {
+				div = hosc_div;
+				src = 1;
+			} else {
+				div = losc_div;
+				src = 0;
+			}
 		} else {
-			div = losc_div;
-			src = 0;
+			/* lowest time as best approximation to "off" */
+			div = 0;
+			src = 1;
 		}
 
 		writel(src | div << 4,
 		       pctl->membase +
 		       sunxi_irq_debounce_reg_from_bank(pctl->desc, i));
+
+		pr_info("Debounce filter for IRQ bank %d configured to %d us (reg %x)\n",
+			i, debounce, src | div << 4);
 	}
 
 	return 0;
-- 
2.30.2


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Re: [PATCH v2] pinctrl: sunxi: set minimal debounce on input-debounce 0

[Maxime Ripard]

Hi,

On Sun, Feb 12, 2023 at 07:21:03PM +0100, Andreas Feldner wrote:
> sunxi-h3-h5 based boards have no support for switching
> off IRQ debouncing filter. This would be the expected
> behaviour of value 0 for the general pinctl parameter
> input-debounce.
> The current driver implementation ignores value 0
> for input-debounce, leaving the chip's default. This
> default, however, is not minimal, but equivalent to
> value 31 (microseconds).
> 
> This patch does not ignore value 0 but instead makes
> sure the corresponding IRQ debounce filter is set
> to the shortest time selectable, i. e. the fast
> oscillator with a divider of 1 == (2 ^ 0).
> 
> Fixes: 7c926492d38a ("pinctrl: sunxi: Add support for interrupt debouncing")
> 
> Signed-off-by: Andreas Feldner <pelzi@flying-snail.de>

Like I said in the other thread, I don't think that deviating from the
generic property semantics is a good thing.

Maxime

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