bcm27xx: add support for linux v5.15

Build system: x86_64
Build-tested: bcm2708, bcm2709, bcm2710, bcm2711
Run-tested: bcm2708/RPiB+, bcm2709/RPi3B, bcm2710/RPi3B, bcm2711/RPi4B

Signed-off-by: Marty Jones <mj8263788@gmail.com>
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>

1 files changed, 58 insertions, 0 deletions

diff --git a/target/linux/bcm27xx/patches-5.15/950-0029-Revert-mailbox-avoid-timer-start-from-callback.patch b/target/linux/bcm27xx/patches-5.15/950-0029-Revert-mailbox-avoid-timer-start-from-callback.patch
new file mode 100644
index 0000000000..cd121d02c5
--- /dev/null
+++ b/target/linux/bcm27xx/patches-5.15/950-0029-Revert-mailbox-avoid-timer-start-from-callback.patch
@@ -0,0 +1,58 @@
+From fe19823f6053fe91a671fdbf92ab93b517a25219 Mon Sep 17 00:00:00 2001
+From: Phil Elwell <phil@raspberrypi.com>
+Date: Tue, 3 Nov 2020 11:49:53 +0000
+Subject: [PATCH] Revert "mailbox: avoid timer start from callback"
+
+This reverts commit c7dacf5b0f32957b24ef29df1207dc2cd8307743.
+
+The Pi 400 shutdown/poweroff mechanism relies on being able to set
+a GPIO on the expander in the pm_power_off handler, something that
+requires two mailbox calls - GET_GPIO_STATE and SET_GPIO_STATE. A
+recent kernel change introduces a reasonable possibility that the
+GET call doesn't completes, and bisecting led to a commit from
+October that changes the timer usage of the mailbox.
+
+My theory is that there is a race condition in the new code that breaks
+the poll timer, but that it normally goes unnoticed because subsequent
+mailbox activity wakes it up again. The power-off mailbox calls happen
+at a time when other subsystems have been shut down, so if one of them
+fails then there is nothing to allow it to recover.
+
+See: https://github.com/raspberrypi/linux/issues/3941
+
+Signed-off-by: Phil Elwell <phil@raspberrypi.com>
+---
+ drivers/mailbox/mailbox.c | 12 +++++-------
+ 1 file changed, 5 insertions(+), 7 deletions(-)
+
+--- a/drivers/mailbox/mailbox.c
++++ b/drivers/mailbox/mailbox.c
+@@ -82,12 +82,9 @@ static void msg_submit(struct mbox_chan
+ exit:
+ 	spin_unlock_irqrestore(&chan->lock, flags);
+ 
+-	/* kick start the timer immediately to avoid delays */
+-	if (!err && (chan->txdone_method & TXDONE_BY_POLL)) {
+-		/* but only if not already active */
+-		if (!hrtimer_active(&chan->mbox->poll_hrt))
+-			hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
+-	}
++	if (!err && (chan->txdone_method & TXDONE_BY_POLL))
++		/* kick start the timer immediately to avoid delays */
++		hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
+ }
+ 
+ static void tx_tick(struct mbox_chan *chan, int r)
+@@ -125,10 +122,11 @@ static enum hrtimer_restart txdone_hrtim
+ 		struct mbox_chan *chan = &mbox->chans[i];
+ 
+ 		if (chan->active_req && chan->cl) {
+-			resched = true;
+ 			txdone = chan->mbox->ops->last_tx_done(chan);
+ 			if (txdone)
+ 				tx_tick(chan, 0);
++			else
++				resched = true;
+ 		}
+ 	}
+