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74 lines
2.5 KiB
Diff
74 lines
2.5 KiB
Diff
6 years ago
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From 659c52fe8a86264c5119c0592654898d09fe8f28 Mon Sep 17 00:00:00 2001
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From: Eric Anholt <eric@anholt.net>
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Date: Fri, 13 Oct 2017 17:12:55 -0700
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Subject: [PATCH 176/454] drm/vc4: Fix sleeps during the IRQ handler for DSI
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transactions.
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VC4's DSI1 has a bug where the AXI connection is broken for 32-bit
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writes from the CPU, so we use the DMA engine to DMA 32-bit values
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into registers instead. That sleeps, so we can't do it from the top
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half.
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As a solution, use an interrupt thread so that all our writes happen
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when sleeping is is allowed.
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v2: Use IRQF_ONESHOT (suggested by Boris)
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v3: Style nitpicks.
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Signed-off-by: Eric Anholt <eric@anholt.net>
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Link: https://patchwork.freedesktop.org/patch/msgid/20171014001255.32005-1-eric@anholt.net
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Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com> (v2)
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(cherry picked from commit af0c8c10564aac5b6d67308129ec09c4ad5db476)
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---
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drivers/gpu/drm/vc4/vc4_dsi.c | 32 ++++++++++++++++++++++++++++++--
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1 file changed, 30 insertions(+), 2 deletions(-)
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--- a/drivers/gpu/drm/vc4/vc4_dsi.c
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+++ b/drivers/gpu/drm/vc4/vc4_dsi.c
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@@ -1383,6 +1383,27 @@ static void dsi_handle_error(struct vc4_
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*ret = IRQ_HANDLED;
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}
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+/*
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+ * Initial handler for port 1 where we need the reg_dma workaround.
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+ * The register DMA writes sleep, so we can't do it in the top half.
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+ * Instead we use IRQF_ONESHOT so that the IRQ gets disabled in the
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+ * parent interrupt contrller until our interrupt thread is done.
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+ */
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+static irqreturn_t vc4_dsi_irq_defer_to_thread_handler(int irq, void *data)
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+{
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+ struct vc4_dsi *dsi = data;
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+ u32 stat = DSI_PORT_READ(INT_STAT);
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+
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+ if (!stat)
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+ return IRQ_NONE;
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+
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+ return IRQ_WAKE_THREAD;
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+}
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+
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+/*
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+ * Normal IRQ handler for port 0, or the threaded IRQ handler for port
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+ * 1 where we need the reg_dma workaround.
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+ */
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static irqreturn_t vc4_dsi_irq_handler(int irq, void *data)
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{
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struct vc4_dsi *dsi = data;
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@@ -1566,8 +1587,15 @@ static int vc4_dsi_bind(struct device *d
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/* Clear any existing interrupt state. */
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DSI_PORT_WRITE(INT_STAT, DSI_PORT_READ(INT_STAT));
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- ret = devm_request_irq(dev, platform_get_irq(pdev, 0),
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- vc4_dsi_irq_handler, 0, "vc4 dsi", dsi);
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+ if (dsi->reg_dma_mem)
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+ ret = devm_request_threaded_irq(dev, platform_get_irq(pdev, 0),
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+ vc4_dsi_irq_defer_to_thread_handler,
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+ vc4_dsi_irq_handler,
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+ IRQF_ONESHOT,
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+ "vc4 dsi", dsi);
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+ else
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+ ret = devm_request_irq(dev, platform_get_irq(pdev, 0),
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+ vc4_dsi_irq_handler, 0, "vc4 dsi", dsi);
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if (ret) {
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if (ret != -EPROBE_DEFER)
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dev_err(dev, "Failed to get interrupt: %d\n", ret);
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