[PATCH 2/2] drm/mgag200: Add vblank support
Ville Syrjälä
ville.syrjala at linux.intel.com
Tue Sep 10 14:01:03 UTC 2019
On Mon, Sep 09, 2019 at 04:06:33PM +0200, Thomas Zimmermann wrote:
> Support for vblank requires VSYNC to signal an interrupt, which is broken
> on Matrox chipsets.
I don't remember there being anything wrong with the vsync interrupt.
What makes you think it's broken?
> The workaround that is used here and in other free
> Matrox drivers is to program <linecomp> to the value of <vdisplay> and
> enable the VLINE interrupt. This triggers an interrupt at the same time
> when VSYNC begins.
You're programming it to fire at start of vblank, not start of vsync.
>
> VLINE uses separate registers for enabling and clearing pending interrupts.
> No extra syncronization between irq handler and the rest of the driver is
> required.
>
> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> ---
> drivers/gpu/drm/mgag200/mgag200_drv.c | 1 +
> drivers/gpu/drm/mgag200/mgag200_drv.h | 1 +
> drivers/gpu/drm/mgag200/mgag200_main.c | 33 ++++++++++++++++++++
> drivers/gpu/drm/mgag200/mgag200_mode.c | 42 +++++++++++++++++++++++---
> 4 files changed, 73 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.c b/drivers/gpu/drm/mgag200/mgag200_drv.c
> index 4f9df3b93598..cff265973154 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_drv.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_drv.c
> @@ -67,6 +67,7 @@ static struct drm_driver driver = {
> .driver_features = DRIVER_GEM | DRIVER_MODESET,
> .load = mgag200_driver_load,
> .unload = mgag200_driver_unload,
> + .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 1c93f8dc08c7..88cf256d135f 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_drv.h
> +++ b/drivers/gpu/drm/mgag200/mgag200_drv.h
> @@ -195,6 +195,7 @@ 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 a9773334dedf..5941607796e8 100644
> --- a/drivers/gpu/drm/mgag200/mgag200_main.c
> +++ b/drivers/gpu/drm/mgag200/mgag200_main.c
> @@ -10,7 +10,9 @@
>
> #include <drm/drm_crtc_helper.h>
> #include <drm/drm_gem_framebuffer_helper.h>
> +#include <drm/drm_irq.h>
> #include <drm/drm_pci.h>
> +#include <drm/drm_vblank.h>
>
> #include "mgag200_drv.h"
>
> @@ -186,10 +188,18 @@ int mgag200_driver_load(struct drm_device *dev, unsigned long flags)
> }
> mdev->cursor.pixels_current = NULL;
>
> + r = drm_vblank_init(dev, 1);
> + if (r)
> + goto err_modeset;
> +
> r = drm_fbdev_generic_setup(mdev->dev, 0);
> if (r)
> goto err_modeset;
>
> + r = drm_irq_install(dev, dev->pdev->irq);
> + if (r)
> + goto err_modeset;
> +
> return 0;
>
> err_modeset:
> @@ -207,8 +217,31 @@ 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_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, iclear;
> +
> + status = RREG32(0x1e14);
> +
> + if (status & 0x00000020) { /* test <vlinepen> */
> + drm_for_each_crtc(crtc, dev) {
> + drm_crtc_handle_vblank(crtc);
> + }
A bit odd way to write that but as long this driver doesn't support
crtc2 it should be fine.
> + iclear = RREG32(0x1e18);
> + iclear |= 0x00000020; /* set <vlineiclr> */
> + WREG32(0x1e18, iclear);
> + return IRQ_HANDLED;
> + }
> +
> + return IRQ_NONE;
> +};
> diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c
> index 5e778b5f1a10..ffe5f15d0a7d 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 +1043,13 @@ static int mga_crtc_mode_set(struct drm_crtc *crtc,
> vsyncend = mode->vsync_end - 1;
> vtotal = mode->vtotal - 2;
>
> + /* The VSYNC interrupt is broken on Matrox chipsets. We use
> + * the VLINE interrupt instead. It triggers when the current
> + * linecomp has been reached. Therefore keep <linecomp> in
> + * sync with <vdisplay>.
> + */
> + linecomp = vdisplay;
I have an odd recollection that you want vdisplay+1 here if you
want the interrupt to fire at the correct time.
Sine linecomp also resets the memory address counter to 0 you
should probably see one bogus line at the bottom of the screen
if my recollection of that +1 is correct.
But maybe my memory is wrong.
> +
> WREG_GFX(0, 0);
> WREG_GFX(1, 0);
> WREG_GFX(2, 0);
> @@ -1063,12 +1071,12 @@ 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 +1091,7 @@ 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 +1107,7 @@ 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 +1419,30 @@ 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 ien;
> +
> + ien = RREG32(0x1e1c);
MGAREG_IEN?
> + ien |= 0x00000020; /* set <vlineien> */
> + WREG32(0x1e1c, 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(0x1e1c);
> + ien &= 0xffffffdf; /* clear <vlineien> */
> + WREG32(0x1e1c, ien);
> +}
> +
> /* These provide the minimum set of functions required to handle a CRTC */
> static const struct drm_crtc_funcs mga_crtc_funcs = {
> .cursor_set = mga_crtc_cursor_set,
> @@ -1418,6 +1450,8 @@ 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 = {
> --
> 2.23.0
>
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--
Ville Syrjälä
Intel
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