From 659c52fe8a86264c5119c0592654898d09fe8f28 Mon Sep 17 00:00:00 2001 From: Eric Anholt Date: Fri, 13 Oct 2017 17:12:55 -0700 Subject: [PATCH 176/454] drm/vc4: Fix sleeps during the IRQ handler for DSI transactions. 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 Link: https://patchwork.freedesktop.org/patch/msgid/20171014001255.32005-1-eric@anholt.net Reviewed-by: Boris Brezillon (v2) (cherry picked from commit af0c8c10564aac5b6d67308129ec09c4ad5db476) --- drivers/gpu/drm/vc4/vc4_dsi.c | 32 ++++++++++++++++++++++++++++++-- 1 file changed, 30 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/vc4/vc4_dsi.c +++ b/drivers/gpu/drm/vc4/vc4_dsi.c @@ -1383,6 +1383,27 @@ static void dsi_handle_error(struct vc4_ *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; @@ -1566,8 +1587,15 @@ static int vc4_dsi_bind(struct device *d /* 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);