[PATCH v3 3/4] drm/mgag200: Add vblank support

[Thomas Zimmermann <tzimmermann@suse.de>]

There's no VBLANK interrupt on Matrox chipsets. The workaround that is
being used here and in other free Matrox drivers is to program <linecomp>
to the value of <vdisplay> + 1 and enable the VLINE interrupt. This
triggers an interrupt at the time when VBLANK begins.

VLINE uses separate registers for enabling and clearing pending interrupts.
No extra syncihronization between irq handler and the rest of the driver is
required.

v3:
	* set <linecomp> to <vdisplay> + 1 to trigger at VBLANK
	* expand comment on linecomp
v2:
	* only signal vblank on CRTC 0
	* use constants for registers and fields
	* set VLINECLR before enabling interrupt
	* test against STATUS and IEN in irq handler
	* coding-style fixes

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
---
 drivers/gpu/drm/mgag200/mgag200_drv.c  |  1 +
 drivers/gpu/drm/mgag200/mgag200_drv.h  |  1 +
 drivers/gpu/drm/mgag200/mgag200_main.c | 40 +++++++++++++++++++++
 drivers/gpu/drm/mgag200/mgag200_mode.c | 48 +++++++++++++++++++++++---
 drivers/gpu/drm/mgag200/mgag200_reg.h  |  5 +++
 5 files changed, 91 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.c b/drivers/gpu/drm/mgag200/mgag200_drv.c
index 8e641b29eb01..15cb39c08989 100644
--- a/drivers/gpu/drm/mgag200/mgag200_drv.c
+++ b/drivers/gpu/drm/mgag200/mgag200_drv.c
@@ -133,6 +133,7 @@ int mgag200_driver_dumb_create(struct drm_file *file,
 
 static struct drm_driver driver = {
 	.driver_features = DRIVER_GEM | DRIVER_MODESET,
+	.irq_handler = mgag200_irq_handler,
 	.fops = &mgag200_driver_fops,
 	.name = DRIVER_NAME,
 	.desc = DRIVER_DESC,
diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.h b/drivers/gpu/drm/mgag200/mgag200_drv.h
index aa32aad222c2..8af57dfe0d09 100644
--- a/drivers/gpu/drm/mgag200/mgag200_drv.h
+++ b/drivers/gpu/drm/mgag200/mgag200_drv.h
@@ -206,6 +206,7 @@ void mgag200_modeset_fini(struct mga_device *mdev);
 				/* mgag200_main.c */
 int mgag200_driver_load(struct drm_device *dev, unsigned long flags);
 void mgag200_driver_unload(struct drm_device *dev);
+irqreturn_t mgag200_irq_handler(int irq, void *arg);
 
 				/* mgag200_i2c.c */
 struct mga_i2c_chan *mgag200_i2c_create(struct drm_device *dev);
diff --git a/drivers/gpu/drm/mgag200/mgag200_main.c b/drivers/gpu/drm/mgag200/mgag200_main.c
index b680cf47cbb9..72ebcd015fba 100644
--- a/drivers/gpu/drm/mgag200/mgag200_main.c
+++ b/drivers/gpu/drm/mgag200/mgag200_main.c
@@ -12,6 +12,8 @@
 
 #include <drm/drm_crtc_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_irq.h>
+#include <drm/drm_vblank.h>
 
 #include "mgag200_drv.h"
 
@@ -181,6 +183,14 @@ int mgag200_driver_load(struct drm_device *dev, unsigned long flags)
 		dev_warn(&dev->pdev->dev,
 			"Could not initialize cursors. Not doing hardware cursors.\n");
 
+	r = drm_vblank_init(dev, 1);
+	if (r)
+		goto err_modeset;
+
+	r = drm_irq_install(dev, dev->pdev->irq);
+	if (r)
+		goto err_modeset;
+
 	return 0;
 
 err_modeset:
@@ -199,9 +209,39 @@ void mgag200_driver_unload(struct drm_device *dev)
 
 	if (mdev == NULL)
 		return;
+	drm_irq_uninstall(dev);
 	mgag200_modeset_fini(mdev);
 	drm_mode_config_cleanup(dev);
 	mgag200_cursor_fini(mdev);
 	mgag200_mm_fini(mdev);
 	dev->dev_private = NULL;
 }
+
+irqreturn_t mgag200_irq_handler(int irq, void *arg)
+{
+	struct drm_device *dev = arg;
+	struct mga_device *mdev = dev->dev_private;
+	struct drm_crtc *crtc;
+	u32 status, ien, iclear;
+
+	status = RREG32(MGAREG_STATUS);
+
+	if (status & MGA_VLINEPEN) {
+		ien = RREG32(MGAREG_IEN);
+		if (!(ien & MGA_VLINEIEN))
+			goto out;
+
+		crtc = drm_crtc_from_index(dev, 0);
+		if (WARN_ON_ONCE(!crtc))
+			goto out;
+		drm_crtc_handle_vblank(crtc);
+
+		iclear = RREG32(MGAREG_ICLEAR);
+		iclear |= MGA_VLINECLR;
+		WREG32(MGAREG_ICLEAR, iclear);
+		return IRQ_HANDLED;
+	}
+
+out:
+	return IRQ_NONE;
+};
diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
index 9c4440d7b7b4..4d0b9e497149 100644
--- a/drivers/gpu/drm/mgag200/mgag200_mode.c
+++ b/drivers/gpu/drm/mgag200/mgag200_mode.c
@@ -905,6 +905,7 @@ static int mga_crtc_mode_set(struct drm_crtc *crtc,
 	const struct drm_framebuffer *fb = crtc->primary->fb;
 	int hdisplay, hsyncstart, hsyncend, htotal;
 	int vdisplay, vsyncstart, vsyncend, vtotal;
+	int linecomp;
 	int pitch;
 	int option = 0, option2 = 0;
 	int i;
@@ -1042,6 +1043,15 @@ static int mga_crtc_mode_set(struct drm_crtc *crtc,
 	vsyncend = mode->vsync_end - 1;
 	vtotal = mode->vtotal - 2;
 
+	/*
+	 * There's no VBLANK interrupt on Matrox chipsets, so we use
+	 * the VLINE interrupt instead. It triggers when the current
+	 * linecomp has been reached. For VBLANK, this is the first
+	 * non-visible line at the bottom of the screen. Therefore,
+	 * keep <linecomp> in sync with <vdisplay>.
+	 */
+	linecomp = vdisplay + 1;
+
 	WREG_GFX(0, 0);
 	WREG_GFX(1, 0);
 	WREG_GFX(2, 0);
@@ -1063,12 +1073,12 @@ static int mga_crtc_mode_set(struct drm_crtc *crtc,
 		 ((vdisplay & 0x100) >> 7) |
 		 ((vsyncstart & 0x100) >> 6) |
 		 ((vdisplay & 0x100) >> 5) |
-		 ((vdisplay & 0x100) >> 4) | /* linecomp */
+		 ((linecomp & 0x100) >> 4) |
 		 ((vtotal & 0x200) >> 4)|
 		 ((vdisplay & 0x200) >> 3) |
 		 ((vsyncstart & 0x200) >> 2));
 	WREG_CRT(9, ((vdisplay & 0x200) >> 4) |
-		 ((vdisplay & 0x200) >> 3));
+		 ((linecomp & 0x200) >> 3));
 	WREG_CRT(10, 0);
 	WREG_CRT(11, 0);
 	WREG_CRT(12, 0);
@@ -1083,7 +1093,7 @@ static int mga_crtc_mode_set(struct drm_crtc *crtc,
 	WREG_CRT(21, vdisplay & 0xFF);
 	WREG_CRT(22, (vtotal + 1) & 0xFF);
 	WREG_CRT(23, 0xc3);
-	WREG_CRT(24, vdisplay & 0xFF);
+	WREG_CRT(24, linecomp & 0xff);
 
 	ext_vga[0] = 0;
 	ext_vga[5] = 0;
@@ -1099,7 +1109,7 @@ static int mga_crtc_mode_set(struct drm_crtc *crtc,
 		((vdisplay & 0x400) >> 8) |
 		((vdisplay & 0xc00) >> 7) |
 		((vsyncstart & 0xc00) >> 5) |
-		((vdisplay & 0x400) >> 3);
+		((linecomp & 0x400) >> 3);
 	if (fb->format->cpp[0] * 8 == 24)
 		ext_vga[3] = (((1 << bppshift) * 3) - 1) | 0x80;
 	else
@@ -1411,6 +1421,34 @@ static void mga_crtc_disable(struct drm_crtc *crtc)
 	crtc->primary->fb = NULL;
 }
 
+static int mga_crtc_enable_vblank(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct mga_device *mdev = dev->dev_private;
+	u32 iclear, ien;
+
+	iclear = RREG32(MGAREG_ICLEAR);
+	iclear |= MGA_VLINECLR;
+	WREG32(MGAREG_ICLEAR, iclear);
+
+	ien = RREG32(MGAREG_IEN);
+	ien |= MGA_VLINEIEN;
+	WREG32(MGAREG_IEN, ien);
+
+	return 0;
+}
+
+static void mga_crtc_disable_vblank(struct drm_crtc *crtc)
+{
+	struct drm_device *dev = crtc->dev;
+	struct mga_device *mdev = dev->dev_private;
+	u32 ien;
+
+	ien = RREG32(MGAREG_IEN);
+	ien &= ~(MGA_VLINEIEN);
+	WREG32(MGAREG_IEN, ien);
+}
+
 /* These provide the minimum set of functions required to handle a CRTC */
 static const struct drm_crtc_funcs mga_crtc_funcs = {
 	.cursor_set = mgag200_crtc_cursor_set,
@@ -1418,6 +1456,8 @@ static const struct drm_crtc_funcs mga_crtc_funcs = {
 	.gamma_set = mga_crtc_gamma_set,
 	.set_config = drm_crtc_helper_set_config,
 	.destroy = mga_crtc_destroy,
+	.enable_vblank = mga_crtc_enable_vblank,
+	.disable_vblank = mga_crtc_disable_vblank,
 };
 
 static const struct drm_crtc_helper_funcs mga_helper_funcs = {
diff --git a/drivers/gpu/drm/mgag200/mgag200_reg.h b/drivers/gpu/drm/mgag200/mgag200_reg.h
index 6c460d9a2143..44db1d8279fa 100644
--- a/drivers/gpu/drm/mgag200/mgag200_reg.h
+++ b/drivers/gpu/drm/mgag200/mgag200_reg.h
@@ -122,6 +122,11 @@
 
 #define MGAREG_MEMCTL           0x2e08
 
+/* Interrupt fields */
+#define MGA_VLINEPEN		(0x01 << 5)
+#define MGA_VLINECLR		(0x01 << 5)
+#define MGA_VLINEIEN		(0x01 << 5)
+
 /* OPMODE register additives */
 
 #define MGAOPM_DMA_GENERAL	(0x00 << 2)
-- 
2.23.0

_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel