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authorEric Anholt <eric@anholt.net>2017-10-13 17:12:55 -0700
committerEric Anholt <eric@anholt.net>2017-10-19 13:20:09 -0700
commitaf0c8c10564aac5b6d67308129ec09c4ad5db476 (patch)
tree39407dbc8d0c72b2b190dbfa64822a4038e16e1d
parentb9f19259b84dc648f207a46f3581d15eeaedf4b6 (diff)
drm/vc4: Fix sleeps during the IRQ handler for DSI transactions.drm-misc-next-2017-10-20
VC4's DSI1 has a bug where the AXI connection is broken for 32-bit writes from the CPU, so we use the DMA engine to DMA 32-bit values into registers instead. That sleeps, so we can't do it from the top half. As a solution, use an interrupt thread so that all our writes happen when sleeping is is allowed. v2: Use IRQF_ONESHOT (suggested by Boris) v3: Style nitpicks. Signed-off-by: Eric Anholt <eric@anholt.net> Link: https://patchwork.freedesktop.org/patch/msgid/20171014001255.32005-1-eric@anholt.net Reviewed-by: Boris Brezillon <boris.brezillon@free-electrons.com> (v2)
-rw-r--r--drivers/gpu/drm/vc4/vc4_dsi.c32
1 files changed, 30 insertions, 2 deletions
diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
index 554605af344e..94085f8bcd68 100644
--- a/drivers/gpu/drm/vc4/vc4_dsi.c
+++ b/drivers/gpu/drm/vc4/vc4_dsi.c
@@ -1360,6 +1360,27 @@ static void dsi_handle_error(struct vc4_dsi *dsi,
*ret = IRQ_HANDLED;
}
+/*
+ * Initial handler for port 1 where we need the reg_dma workaround.
+ * The register DMA writes sleep, so we can't do it in the top half.
+ * Instead we use IRQF_ONESHOT so that the IRQ gets disabled in the
+ * parent interrupt contrller until our interrupt thread is done.
+ */
+static irqreturn_t vc4_dsi_irq_defer_to_thread_handler(int irq, void *data)
+{
+ struct vc4_dsi *dsi = data;
+ u32 stat = DSI_PORT_READ(INT_STAT);
+
+ if (!stat)
+ return IRQ_NONE;
+
+ return IRQ_WAKE_THREAD;
+}
+
+/*
+ * Normal IRQ handler for port 0, or the threaded IRQ handler for port
+ * 1 where we need the reg_dma workaround.
+ */
static irqreturn_t vc4_dsi_irq_handler(int irq, void *data)
{
struct vc4_dsi *dsi = data;
@@ -1539,8 +1560,15 @@ static int vc4_dsi_bind(struct device *dev, struct device *master, void *data)
/* Clear any existing interrupt state. */
DSI_PORT_WRITE(INT_STAT, DSI_PORT_READ(INT_STAT));
- ret = devm_request_irq(dev, platform_get_irq(pdev, 0),
- vc4_dsi_irq_handler, 0, "vc4 dsi", dsi);
+ if (dsi->reg_dma_mem)
+ ret = devm_request_threaded_irq(dev, platform_get_irq(pdev, 0),
+ vc4_dsi_irq_defer_to_thread_handler,
+ vc4_dsi_irq_handler,
+ IRQF_ONESHOT,
+ "vc4 dsi", dsi);
+ else
+ ret = devm_request_irq(dev, platform_get_irq(pdev, 0),
+ vc4_dsi_irq_handler, 0, "vc4 dsi", dsi);
if (ret) {
if (ret != -EPROBE_DEFER)
dev_err(dev, "Failed to get interrupt: %d\n", ret);

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