There are two problems with the current vfe_disable_output() routine.

Firstly we rightly use a spinlock to protect output->gen2.active_num everywhere except for in the IDLE timeout path of vfe_disable_output(). Even if that is not racy "in practice" somehow it is by happenstance not by design.

Secondly we do not get consistent behaviour from this routine. On sc8280xp 50% of the time I get "VFE idle timeout - resetting". In this case the subsequent capture will succeed. The other 50% of the time, we don't hit the idle timeout, never do the VFE reset and subsequent captures stall indefinitely.

Rewrite the vfe_disable_output() routine to

- Quiesce write masters with vfe_wm_stop() - Set active_num = 0

remembering to hold the spinlock when we do so followed by

- Reset the VFE

Testing on sc8280xp and sdm845 shows this to be a valid fix.

Fixes: 7319cdf189bb ("media: camss: Add support for VFE hardware version Titan 170") Cc: stable@vger.kernel.org Signed-off-by: Bryan O'Donoghue bryan.odonoghue@linaro.org --- .../media/platform/qcom/camss/camss-vfe-170.c | 22 +++---------------- 1 file changed, 3 insertions(+), 19 deletions(-)

diff --git a/drivers/media/platform/qcom/camss/camss-vfe-170.c b/drivers/media/platform/qcom/camss/camss-vfe-170.c index 02494c89da91c..168baaa80d4e6 100644 --- a/drivers/media/platform/qcom/camss/camss-vfe-170.c +++ b/drivers/media/platform/qcom/camss/camss-vfe-170.c @@ -7,7 +7,6 @@ * Copyright (C) 2020-2021 Linaro Ltd. */

-#include <linux/delay.h> #include <linux/interrupt.h> #include <linux/io.h> #include <linux/iopoll.h> @@ -494,35 +493,20 @@ static int vfe_enable_output(struct vfe_line *line) return 0; }

-static int vfe_disable_output(struct vfe_line *line) +static void vfe_disable_output(struct vfe_line *line) { struct vfe_device *vfe = to_vfe(line); struct vfe_output *output = &line->output; unsigned long flags; unsigned int i; - bool done; - int timeout = 0; - - do { - spin_lock_irqsave(&vfe->output_lock, flags); - done = !output->gen2.active_num; - spin_unlock_irqrestore(&vfe->output_lock, flags); - usleep_range(10000, 20000); - - if (timeout++ == 100) { - dev_err(vfe->camss->dev, "VFE idle timeout - resetting\n"); - vfe_reset(vfe); - output->gen2.active_num = 0; - return 0; - } - } while (!done);

spin_lock_irqsave(&vfe->output_lock, flags); for (i = 0; i < output->wm_num; i++) vfe_wm_stop(vfe, output->wm_idx[i]); + output->gen2.active_num = 0; spin_unlock_irqrestore(&vfe->output_lock, flags);

- return 0; + vfe_reset(vfe); }

/*