target/linux/bcm27xx/patches-6.1/950-0704-pinctrl-bcm2835-Workaround-for-edge-IRQ-loss.patch

   1 From dcb717bc899cd55a969fb4f1f8526f313efe148c Mon Sep 17 00:00:00 2001
   2 From: Phil Elwell <phil@raspberrypi.com>
   3 Date: Fri, 5 May 2023 11:25:48 +0100
   4 Subject: [PATCH] pinctrl: bcm2835: Workaround for edge IRQ loss
   5
   6 It has been observed that edge events can be lost when GPIO edges occur
   7 close to each other. Investigation suggests this is due to a hardware
   8 bug, although no mechanism has been identified.
   9
  10 Work around the event loss by moving the IRQ acknowledgement into the
  11 main ISR, adding missing events by explicit level-change detection.
  12
  13 See: https://forums.raspberrypi.com/viewtopic.php?t=350295
  14
  15 Signed-off-by: Phil Elwell <phil@raspberrypi.com>
  16 ---
  17  drivers/pinctrl/bcm/pinctrl-bcm2835.c | 23 ++++++++++++++++++-----
  18  1 file changed, 18 insertions(+), 5 deletions(-)
  19
  20 --- a/drivers/pinctrl/bcm/pinctrl-bcm2835.c
  21 +++ b/drivers/pinctrl/bcm/pinctrl-bcm2835.c
  22 @@ -420,15 +420,32 @@ static void bcm2835_gpio_irq_handle_bank
  23         unsigned long events;
  24         unsigned offset;
  25         unsigned gpio;
  26 +       u32 levs, levs2;
  27
  28         events = bcm2835_gpio_rd(pc, GPEDS0 + bank * 4);
  29 +       levs = bcm2835_gpio_rd(pc, GPLEV0 + bank * 4);
  30         events &= mask;
  31         events &= pc->enabled_irq_map[bank];
  32 +       bcm2835_gpio_wr(pc, GPEDS0 + bank * 4, events);
  33 +
  34 +retry:
  35         for_each_set_bit(offset, &events, 32) {
  36                 gpio = (32 * bank) + offset;
  37                 generic_handle_domain_irq(pc->gpio_chip.irq.domain,
  38                                           gpio);
  39         }
  40 +       events = bcm2835_gpio_rd(pc, GPEDS0 + bank * 4);
  41 +       levs2 = bcm2835_gpio_rd(pc, GPLEV0 + bank * 4);
  42 +
  43 +       events |= levs2 & ~levs & bcm2835_gpio_rd(pc, GPREN0 + bank * 4);
  44 +       events |= ~levs2 & levs & bcm2835_gpio_rd(pc, GPFEN0 + bank * 4);
  45 +       events &= mask;
  46 +       events &= pc->enabled_irq_map[bank];
  47 +       if (events) {
  48 +               bcm2835_gpio_wr(pc, GPEDS0 + bank * 4, events);
  49 +               levs = levs2;
  50 +               goto retry;
  51 +       }
  52  }
  53
  54  static void bcm2835_gpio_irq_handler(struct irq_desc *desc)
  55 @@ -668,11 +685,7 @@ static int bcm2835_gpio_irq_set_type(str
  56
  57  static void bcm2835_gpio_irq_ack(struct irq_data *data)
  58  {
  59 -       struct gpio_chip *chip = irq_data_get_irq_chip_data(data);
  60 -       struct bcm2835_pinctrl *pc = gpiochip_get_data(chip);
  61 -       unsigned gpio = irqd_to_hwirq(data);
  62 -
  63 -       bcm2835_gpio_set_bit(pc, GPEDS0, gpio);
  64 +       /* Nothing to do - the main interrupt handler includes the ACK */
  65  }
  66
  67  static int bcm2835_gpio_irq_set_wake(struct irq_data *data, unsigned int on)