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From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: dri-devel@lists.freedesktop.org
Cc: Marek Vasut <marex@denx.de>, kernel@pengutronix.de, linux-imx@nxp.com
Subject: [PATCH 13/21] drm: mxsfb: Don't touch AXI clock in IRQ context
Date: Mon,  9 Mar 2020 21:52:08 +0200
Message-ID: <20200309195216.31042-14-laurent.pinchart@ideasonboard.com> (raw)
In-Reply-To: <20200309195216.31042-1-laurent.pinchart@ideasonboard.com>

The driver attempts agressive power management by enabling and disabling
the AXI clock around register accesses. This results in attempts to
enable and disable the clock in the IRQ handler, which is a no-go as
preparing or unpreparing the clock may sleep.

On the other hand, the driver enables the AXI clock when enabling the
CRTC and keeps it enabled until the CRTC is disabled. This is correct,
and renders the power management attempt pointless, as interrupts are
not supposed to occur when the CRTC is off.

The same reasoning can be applied to the CRTC .enable_vblank() and
.disable_vblank() that are not supposed to be called when the CRTC off
and thus don't require manual handling of the AXI clock. Furthermore,
vblank handling is never enabled, which results in the vblank enable and
disable handlers never being called.

To fix this, remove the manual clock handling in the IRQ, the CRTC
.enable_vblank() and .disable_vblank() handlers and the plane
.atomic_update() handler. We however need to handle the clock manually
in mxsfb_irq_disable() as is calls .disable_vblank() manually and is
used both at probe and remove time.

The clock disabling is also moved to the last step of the
mxsfb_crtc_atomic_disable() function, to prepare for enabling vblank
handling.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
 drivers/gpu/drm/mxsfb/mxsfb_drv.c |  6 ++----
 drivers/gpu/drm/mxsfb/mxsfb_kms.c | 15 ++++-----------
 2 files changed, 6 insertions(+), 15 deletions(-)

diff --git a/drivers/gpu/drm/mxsfb/mxsfb_drv.c b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
index a8da92976d13..e324bd2a63a5 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_drv.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_drv.c
@@ -231,7 +231,9 @@ static void mxsfb_irq_disable(struct drm_device *drm)
 {
 	struct mxsfb_drm_private *mxsfb = drm->dev_private;
 
+	mxsfb_enable_axi_clk(mxsfb);
 	mxsfb->crtc.funcs->disable_vblank(&mxsfb->crtc);
+	mxsfb_disable_axi_clk(mxsfb);
 }
 
 static irqreturn_t mxsfb_irq_handler(int irq, void *data)
@@ -240,8 +242,6 @@ static irqreturn_t mxsfb_irq_handler(int irq, void *data)
 	struct mxsfb_drm_private *mxsfb = drm->dev_private;
 	u32 reg;
 
-	mxsfb_enable_axi_clk(mxsfb);
-
 	reg = readl(mxsfb->base + LCDC_CTRL1);
 
 	if (reg & CTRL1_CUR_FRAME_DONE_IRQ)
@@ -249,8 +249,6 @@ static irqreturn_t mxsfb_irq_handler(int irq, void *data)
 
 	writel(CTRL1_CUR_FRAME_DONE_IRQ, mxsfb->base + LCDC_CTRL1 + REG_CLR);
 
-	mxsfb_disable_axi_clk(mxsfb);
-
 	return IRQ_HANDLED;
 }
 
diff --git a/drivers/gpu/drm/mxsfb/mxsfb_kms.c b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
index ebe0785694cb..ac2696c8483d 100644
--- a/drivers/gpu/drm/mxsfb/mxsfb_kms.c
+++ b/drivers/gpu/drm/mxsfb/mxsfb_kms.c
@@ -344,9 +344,6 @@ static void mxsfb_crtc_atomic_disable(struct drm_crtc *crtc,
 	struct drm_pending_vblank_event *event;
 
 	mxsfb_disable_controller(mxsfb);
-	mxsfb_disable_axi_clk(mxsfb);
-
-	pm_runtime_put_sync(drm->dev);
 
 	spin_lock_irq(&drm->event_lock);
 	event = crtc->state->event;
@@ -355,6 +352,9 @@ static void mxsfb_crtc_atomic_disable(struct drm_crtc *crtc,
 		drm_crtc_send_vblank_event(crtc, event);
 	}
 	spin_unlock_irq(&drm->event_lock);
+
+	mxsfb_disable_axi_clk(mxsfb);
+	pm_runtime_put_sync(drm->dev);
 }
 
 static int mxsfb_crtc_enable_vblank(struct drm_crtc *crtc)
@@ -362,10 +362,8 @@ static int mxsfb_crtc_enable_vblank(struct drm_crtc *crtc)
 	struct mxsfb_drm_private *mxsfb = to_mxsfb_drm_private(crtc->dev);
 
 	/* Clear and enable VBLANK IRQ */
-	mxsfb_enable_axi_clk(mxsfb);
 	writel(CTRL1_CUR_FRAME_DONE_IRQ, mxsfb->base + LCDC_CTRL1 + REG_CLR);
 	writel(CTRL1_CUR_FRAME_DONE_IRQ_EN, mxsfb->base + LCDC_CTRL1 + REG_SET);
-	mxsfb_disable_axi_clk(mxsfb);
 
 	return 0;
 }
@@ -375,10 +373,8 @@ static void mxsfb_crtc_disable_vblank(struct drm_crtc *crtc)
 	struct mxsfb_drm_private *mxsfb = to_mxsfb_drm_private(crtc->dev);
 
 	/* Disable and clear VBLANK IRQ */
-	mxsfb_enable_axi_clk(mxsfb);
 	writel(CTRL1_CUR_FRAME_DONE_IRQ_EN, mxsfb->base + LCDC_CTRL1 + REG_CLR);
 	writel(CTRL1_CUR_FRAME_DONE_IRQ, mxsfb->base + LCDC_CTRL1 + REG_CLR);
-	mxsfb_disable_axi_clk(mxsfb);
 }
 
 static const struct drm_crtc_helper_funcs mxsfb_crtc_helper_funcs = {
@@ -433,11 +429,8 @@ static void mxsfb_plane_atomic_update(struct drm_plane *plane,
 	dma_addr_t paddr;
 
 	paddr = mxsfb_get_fb_paddr(mxsfb);
-	if (paddr) {
-		mxsfb_enable_axi_clk(mxsfb);
+	if (paddr)
 		writel(paddr, mxsfb->base + mxsfb->devdata->next_buf);
-		mxsfb_disable_axi_clk(mxsfb);
-	}
 }
 
 static const struct drm_plane_helper_funcs mxsfb_plane_helper_funcs = {
-- 
Regards,

Laurent Pinchart

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  parent reply index

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-09 19:51 [PATCH 00/21] drm: mxsfb: Add i.MX7 support Laurent Pinchart
2020-03-09 19:51 ` [PATCH 01/21] drm: mxsfb: Remove fbdev leftovers Laurent Pinchart
2020-03-23 20:23   ` Stefan Agner
2020-03-09 19:51 ` [PATCH 02/21] drm: mxsfb: Use drm_panel_bridge Laurent Pinchart
2020-03-23 21:27   ` Stefan Agner
2020-03-23 21:38     ` Sam Ravnborg
2020-03-23 23:50       ` Stefan Agner
2020-05-30  2:14     ` Laurent Pinchart
2020-06-02 13:12       ` Daniel Vetter
2020-06-02 14:34         ` Stefan Agner
2020-06-02 17:18           ` Laurent Pinchart
2020-06-02 17:13         ` Laurent Pinchart
2020-06-03  8:16           ` Daniel Vetter
2020-06-04 20:10             ` Sam Ravnborg
2020-03-09 19:51 ` [PATCH 03/21] drm: mxsfb: Use BIT() macro to define register bitfields Laurent Pinchart
2020-03-23 21:34   ` Stefan Agner
2020-03-09 19:51 ` [PATCH 04/21] drm: mxsfb: Remove unused macros from mxsfb_regs.h Laurent Pinchart
2020-03-23 21:36   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 05/21] drm: mxsfb: Clarify format and bus width configuration Laurent Pinchart
2020-03-23 21:42   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 06/21] drm: mxsfb: Pass mxsfb_drm_private pointer to mxsfb_reset_block() Laurent Pinchart
2020-03-23 21:43   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 07/21] drm: mxsfb: Use LCDC_CTRL register name explicitly Laurent Pinchart
2020-03-23 21:48   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 08/21] drm: mxsfb: Remove register definitions from mxsfb_crtc.c Laurent Pinchart
2020-03-23 21:49   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 09/21] drm: mxsfb: Remove unneeded includes Laurent Pinchart
2020-03-23 21:53   ` Stefan Agner
2020-05-30  0:33     ` Laurent Pinchart
2020-03-09 19:52 ` [PATCH 10/21] drm: mxsfb: Stop using DRM simple display pipeline helper Laurent Pinchart
2020-03-23 22:30   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 11/21] drm: mxsfb: Rename mxsfb_crtc.c to mxsfb_kms.c Laurent Pinchart
2020-03-23 22:31   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 12/21] drm: mxsfb: Move vblank event arm to CRTC .atomic_flush() Laurent Pinchart
2020-03-23 22:38   ` Stefan Agner
2020-03-09 19:52 ` Laurent Pinchart [this message]
2020-03-23 22:50   ` [PATCH 13/21] drm: mxsfb: Don't touch AXI clock in IRQ context Stefan Agner
2020-03-09 19:52 ` [PATCH 14/21] drm: mxsfb: Enable vblank handling Laurent Pinchart
2020-03-23 23:08   ` Stefan Agner
2020-03-24 10:37     ` Stefan Agner
2020-03-09 19:52 ` [PATCH 15/21] drm: mxsfb: Remove mxsfb_devdata unused fields Laurent Pinchart
2020-03-23 23:15   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 16/21] drm: mxsfb: Add i.MX7 to the list of supported SoCs in Kconfig Laurent Pinchart
2020-03-10 16:28   ` Fabio Estevam
2020-03-10 16:32     ` Laurent Pinchart
2020-03-10 16:37       ` [PATCH v1.1 " Laurent Pinchart
2020-03-23 23:18   ` [PATCH " Stefan Agner
2020-03-09 19:52 ` [PATCH 17/21] drm: mxsfb: Update internal IP version number for i.MX6SX Laurent Pinchart
2020-03-23 23:20   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 18/21] drm: mxsfb: Drop non-OF support Laurent Pinchart
2020-03-23 23:23   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 19/21] drm: mxsfb: Turn mxsfb_set_pixel_fmt() into a void function Laurent Pinchart
2020-03-23 23:28   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 20/21] drm: mxsfb: Merge mxsfb_set_pixel_fmt() and mxsfb_set_bus_fmt() Laurent Pinchart
2020-03-23 23:34   ` Stefan Agner
2020-03-09 19:52 ` [PATCH 21/21] drm: mxsfb: Support the alpha plane Laurent Pinchart
2020-03-23 23:48   ` Stefan Agner
2020-05-30  2:44     ` Laurent Pinchart
2020-03-19  9:36 ` [PATCH 00/21] drm: mxsfb: Add i.MX7 support Laurent Pinchart
2020-04-12 16:37 ` Guido Günther
2020-05-26 15:13 ` Stefan Agner
2020-05-30  0:29   ` Laurent Pinchart

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