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76 lines
2.8 KiB
Diff
76 lines
2.8 KiB
Diff
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From 8740c5d8ab750b3e12f7f081082e2ae8c22ab6db Mon Sep 17 00:00:00 2001
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From: Naushir Patuck <naush@raspberrypi.com>
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Date: Fri, 5 Mar 2021 15:40:45 +0000
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Subject: [PATCH] media: bcm2835-unicam: Fix bug in buffer swapping
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logic
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If multiple sets of interrupts occur simultaneously, it may be unsafe
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to swap buffers, as the hardware may already be re-using the current
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buffers. In such cases, avoid swapping buffers, and wait for the next
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opportunity at the Frame End interrupt to signal completion.
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Additionally, check the packet compare status when watching for frame
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end for buffers swaps, as this could also signify a frame end event.
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Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
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---
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.../media/platform/bcm2835/bcm2835-unicam.c | 21 ++++++++++++++++---
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1 file changed, 18 insertions(+), 3 deletions(-)
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--- a/drivers/media/platform/bcm2835/bcm2835-unicam.c
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+++ b/drivers/media/platform/bcm2835/bcm2835-unicam.c
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@@ -798,6 +798,7 @@ static irqreturn_t unicam_isr(int irq, v
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unsigned int sequence = unicam->sequence;
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unsigned int i;
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u32 ista, sta;
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+ bool fe;
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u64 ts;
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sta = reg_read(unicam, UNICAM_STA);
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@@ -815,12 +816,18 @@ static irqreturn_t unicam_isr(int irq, v
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return IRQ_HANDLED;
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/*
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+ * Look for either the Frame End interrupt or the Packet Capture status
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+ * to signal a frame end.
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+ */
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+ fe = (ista & UNICAM_FEI || sta & UNICAM_PI0);
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+
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+ /*
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* We must run the frame end handler first. If we have a valid next_frm
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* and we get a simultaneout FE + FS interrupt, running the FS handler
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* first would null out the next_frm ptr and we would have lost the
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* buffer forever.
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*/
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- if (ista & UNICAM_FEI || sta & UNICAM_PI0) {
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+ if (fe) {
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/*
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* Ensure we have swapped buffers already as we can't
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* stop the peripheral. If no buffer is available, use a
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@@ -831,7 +838,15 @@ static irqreturn_t unicam_isr(int irq, v
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if (!unicam->node[i].streaming)
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continue;
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- if (unicam->node[i].cur_frm)
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+ /*
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+ * If cur_frm == next_frm, it means we have not had
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+ * a chance to swap buffers, likely due to having
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+ * multiple interrupts occurring simultaneously (like FE
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+ * + FS + LS). In this case, we cannot signal the buffer
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+ * as complete, as the HW will reuse that buffer.
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+ */
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+ if (unicam->node[i].cur_frm &&
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+ unicam->node[i].cur_frm != unicam->node[i].next_frm)
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unicam_process_buffer_complete(&unicam->node[i],
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sequence);
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unicam->node[i].cur_frm = unicam->node[i].next_frm;
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@@ -868,7 +883,7 @@ static irqreturn_t unicam_isr(int irq, v
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* where the HW does not actually swap it if the new frame has
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* already started.
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*/
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- if (ista & (UNICAM_FSI | UNICAM_LCI) && !(ista & UNICAM_FEI)) {
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+ if (ista & (UNICAM_FSI | UNICAM_LCI) && !fe) {
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for (i = 0; i < ARRAY_SIZE(unicam->node); i++) {
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if (!unicam->node[i].streaming)
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continue;
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