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59 lines
2.1 KiB
Diff
59 lines
2.1 KiB
Diff
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From a8fb0d43b8acd25d68a0d2c24fd0260393148447 Mon Sep 17 00:00:00 2001
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From: Phil Elwell <phil@raspberrypi.com>
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Date: Tue, 3 Nov 2020 11:49:53 +0000
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Subject: [PATCH] Revert "mailbox: avoid timer start from callback"
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This reverts commit c7dacf5b0f32957b24ef29df1207dc2cd8307743.
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The Pi 400 shutdown/poweroff mechanism relies on being able to set
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a GPIO on the expander in the pm_power_off handler, something that
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requires two mailbox calls - GET_GPIO_STATE and SET_GPIO_STATE. A
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recent kernel change introduces a reasonable possibility that the
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GET call doesn't completes, and bisecting led to a commit from
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October that changes the timer usage of the mailbox.
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My theory is that there is a race condition in the new code that breaks
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the poll timer, but that it normally goes unnoticed because subsequent
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mailbox activity wakes it up again. The power-off mailbox calls happen
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at a time when other subsystems have been shut down, so if one of them
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fails then there is nothing to allow it to recover.
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See: https://github.com/raspberrypi/linux/issues/3941
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Signed-off-by: Phil Elwell <phil@raspberrypi.com>
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---
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drivers/mailbox/mailbox.c | 12 +++++-------
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1 file changed, 5 insertions(+), 7 deletions(-)
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--- a/drivers/mailbox/mailbox.c
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+++ b/drivers/mailbox/mailbox.c
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@@ -82,12 +82,9 @@ static void msg_submit(struct mbox_chan
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exit:
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spin_unlock_irqrestore(&chan->lock, flags);
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- /* kick start the timer immediately to avoid delays */
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- if (!err && (chan->txdone_method & TXDONE_BY_POLL)) {
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- /* but only if not already active */
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- if (!hrtimer_active(&chan->mbox->poll_hrt))
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- hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
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- }
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+ if (!err && (chan->txdone_method & TXDONE_BY_POLL))
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+ /* kick start the timer immediately to avoid delays */
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+ hrtimer_start(&chan->mbox->poll_hrt, 0, HRTIMER_MODE_REL);
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}
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static void tx_tick(struct mbox_chan *chan, int r)
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@@ -125,10 +122,11 @@ static enum hrtimer_restart txdone_hrtim
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struct mbox_chan *chan = &mbox->chans[i];
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if (chan->active_req && chan->cl) {
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- resched = true;
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txdone = chan->mbox->ops->last_tx_done(chan);
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if (txdone)
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tx_tick(chan, 0);
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+ else
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+ resched = true;
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}
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}
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