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011f2c26f1
As usual these patches were extracted and rebased from the raspberry pi repo: https://github.com/raspberrypi/linux/tree/rpi-4.4.y Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
69 lines
2.1 KiB
Diff
69 lines
2.1 KiB
Diff
From 42504be159b0fd85d705265dceec01c74d853478 Mon Sep 17 00:00:00 2001
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From: Eric Anholt <eric@anholt.net>
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Date: Fri, 3 Jun 2016 19:29:11 -0700
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Subject: [PATCH] dmaengine: bcm2835: Fix polling for completion of DMA with
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interrupts masked.
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The tx_status hook is supposed to be safe to call from interrupt
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context, but it wouldn't ever return completion for the last transfer,
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meaning you couldn't poll for DMA completion with interrupts masked.
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This fixes IRQ handling for bcm2835's DSI1, which requires using the
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DMA engine to write its registers due to a bug in the AXI bridge.
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Signed-off-by: Eric Anholt <eric@anholt.net>
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---
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drivers/dma/bcm2835-dma.c | 24 +++++++++++++++++++-----
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1 file changed, 19 insertions(+), 5 deletions(-)
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--- a/drivers/dma/bcm2835-dma.c
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+++ b/drivers/dma/bcm2835-dma.c
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@@ -588,16 +588,16 @@ static enum dma_status bcm2835_dma_tx_st
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struct virt_dma_desc *vd;
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enum dma_status ret;
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unsigned long flags;
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+ u32 residue;
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ret = dma_cookie_status(chan, cookie, txstate);
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- if (ret == DMA_COMPLETE || !txstate)
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+ if (ret == DMA_COMPLETE)
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return ret;
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spin_lock_irqsave(&c->vc.lock, flags);
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vd = vchan_find_desc(&c->vc, cookie);
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if (vd) {
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- txstate->residue =
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- bcm2835_dma_desc_size(to_bcm2835_dma_desc(&vd->tx));
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+ residue = bcm2835_dma_desc_size(to_bcm2835_dma_desc(&vd->tx));
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} else if (c->desc && c->desc->vd.tx.cookie == cookie) {
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struct bcm2835_desc *d = c->desc;
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dma_addr_t pos;
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@@ -609,11 +609,25 @@ static enum dma_status bcm2835_dma_tx_st
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else
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pos = 0;
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- txstate->residue = bcm2835_dma_desc_size_pos(d, pos);
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+ residue = bcm2835_dma_desc_size_pos(d, pos);
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+
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+ /*
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+ * If our non-cyclic transfer is done, then report
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+ * complete and trigger the next tx now. This lets
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+ * the dmaengine API be used synchronously from an IRQ
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+ * handler.
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+ */
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+ if (!d->cyclic && residue == 0) {
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+ vchan_cookie_complete(&c->desc->vd);
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+ bcm2835_dma_start_desc(c);
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+ ret = dma_cookie_status(chan, cookie, txstate);
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+ }
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} else {
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- txstate->residue = 0;
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+ residue = 0;
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}
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+ dma_set_residue(txstate, residue);
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+
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spin_unlock_irqrestore(&c->vc.lock, flags);
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return ret;
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