Re: [PATCH 05/17] drm/mgag200: Clean up mga_set_start_address()

Hi Thomas,

On Wed, Apr 29, 2020 at 04:32:26PM +0200, Thomas Zimmermann wrote:

All register names and fields are now named according to the MGA programming manuals. The function doesn't need the CRTC, so callers pass in the device structure directly. The logging now uses device-specific macros.

Signed-off-by: Thomas Zimmermann tzimmermann@suse.de

drivers/gpu/drm/mgag200/mgag200_drv.h | 5 ++ drivers/gpu/drm/mgag200/mgag200_mode.c | 82 +++++++++++++++----------- 2 files changed, 53 insertions(+), 34 deletions(-)

diff --git a/drivers/gpu/drm/mgag200/mgag200_drv.h b/drivers/gpu/drm/mgag200/mgag200_drv.h index 4403145e3593c..9b957d9fc7e04 100644 --- a/drivers/gpu/drm/mgag200/mgag200_drv.h +++ b/drivers/gpu/drm/mgag200/mgag200_drv.h @@ -61,6 +61,11 @@ WREG8(MGAREG_CRTC_DATA, v); \ } while (0) \

+#define RREG_ECRT(reg, v) \

• do { \

• WREG8(MGAREG_CRTCEXT_INDEX, reg);		\
  

• v = RREG8(MGAREG_CRTCEXT_DATA);			\
  

• } while (0) \

#define WREG_ECRT(reg, v) \ do { \ diff --git a/drivers/gpu/drm/mgag200/mgag200_mode.c b/drivers/gpu/drm/mgag200/mgag200_mode.c index 3d894b37a0812..b16a73c8617d6 100644 --- a/drivers/gpu/drm/mgag200/mgag200_mode.c +++ b/drivers/gpu/drm/mgag200/mgag200_mode.c @@ -819,49 +819,53 @@ static void mga_g200wb_commit(struct drm_crtc *crtc) }

/*

• This is how the framebuffer base address is stored in g200 cards:
• • Assume @offset is the gpu_addr variable of the framebuffer object
• • Then addr is the number of _pixels_ (not bytes) from the start of

• VRAM to the first pixel we want to display. (divided by 2 for 32bit
  

• framebuffers)
  

• • addr is stored in the CRTCEXT0, CRTCC and CRTCD registers
• addr<20> -> CRTCEXT0<6>
• addr<19-16> -> CRTCEXT0<3-0>
• addr<15-8> -> CRTCC<7-0>
• addr<7-0> -> CRTCD<7-0>
• CRTCEXT0 has to be programmed last to trigger an update and make the
• new addr variable take effect.

• • This is how the framebuffer base address is stored in g200 cards:
• • • Assume @offset is the gpu_addr variable of the framebuffer object
• • • Then addr is the number of _pixels_ (not bytes) from the start of

• • VRAM to the first pixel we want to display. (divided by 2 for 32bit
    

• • framebuffers)
    

• • • addr is stored in the CRTCEXT0, CRTCC and CRTCD registers

• •  addr<20> -> CRTCEXT0<6>
    

• •  addr<19-16> -> CRTCEXT0<3-0>
    

• •  addr<15-8> -> CRTCC<7-0>
    

• •  addr<7-0> -> CRTCD<7-0>
    

• • CRTCEXT0 has to be programmed last to trigger an update and make the
• • new addr variable take effect.
  */

-static void mga_set_start_address(struct drm_crtc *crtc, unsigned offset) +static void mgag200_set_startadd(struct mga_device *mdev,

• 		 unsigned long offset)
  

{

• struct mga_device *mdev = crtc->dev->dev_private;
• u32 addr;
• int count;
• u8 crtcext0;

• struct drm_device *dev = mdev->dev;
• uint32_t startadd;
• uint8_t crtcc, crtcd, crtcext0;

• while (RREG8(0x1fda) & 0x08);
• while (!(RREG8(0x1fda) & 0x08));

• startadd = offset / 8;

• count = RREG8(MGAREG_VCOUNT) + 2;
• while (RREG8(MGAREG_VCOUNT) < count);
• WREG8(MGAREG_CRTCEXT_INDEX, 0);
• crtcext0 = RREG8(MGAREG_CRTCEXT_DATA);
• crtcext0 &= 0xB0;
• addr = offset / 8;
• /* Can't store addresses any higher than that...

•   but we also don't have more than 16MB of memory, so it should be fine. */
  

• WARN_ON(addr > 0x1fffff);
• crtcext0 |= (!!(addr & (1<<20)))<<6;
• WREG_CRT(0x0d, (u8)(addr & 0xff));
• WREG_CRT(0x0c, (u8)(addr >> 8) & 0xff);
• WREG_ECRT(0x0, ((u8)(addr >> 16) & 0xf) | crtcext0);

• /*

• * Can't store addresses any higher than that, but we also
  

• * don't have more than 16MB of memory, so it should be fine.
  

• */
  

• drm_WARN_ON(dev, startadd > 0x1fffff);
• RREG_ECRT(0x00, crtcext0);
• crtcc = (startadd >> 8) & 0xff;
• crtcd = startadd & 0xff;
• crtcext0 &= 0xb0;

• crtcext0 |= ((startadd >> 14) & BIT(6)) |

It is not so obvious that the value of bit 20 is stored in bit 6 here.

Maybe: crtcext0 |= ((startadd & BIT(20) >> 14) |

I would find the above easier to parse.

•     ((startadd >> 16) & 0x0f);
  

• WREG_CRT(0x0c, crtcc);
• WREG_CRT(0x0d, crtcd);
• WREG_ECRT(0x00, crtcext0);

}

static int mga_crtc_do_set_base(struct drm_crtc *crtc, struct drm_framebuffer *fb, int x, int y, int atomic) {

• struct mga_device *mdev = crtc->dev->dev_private;

Could you use a crtc_to_mdev() macro here. So we avoid adding new users of dev_private?

struct drm_gem_vram_object *gbo; int ret; s64 gpu_addr;

Make this unsigned long and..

@@ -882,7 +886,7 @@ static int mga_crtc_do_set_base(struct drm_crtc *crtc, goto err_drm_gem_vram_unpin; }

• mga_set_start_address(crtc, (u32)gpu_addr);

• mgag200_set_startadd(mdev, (unsigned long)gpu_addr);

drop this cast.

return 0;

@@ -894,6 +898,16 @@ static int mga_crtc_do_set_base(struct drm_crtc *crtc, static int mga_crtc_mode_set_base(struct drm_crtc *crtc, int x, int y, struct drm_framebuffer *old_fb) {

• struct drm_device *dev = crtc->dev;
• struct mga_device *mdev = dev->dev_private;
• unsigned int count;
• while (RREG8(0x1fda) & 0x08) { }
• while (!(RREG8(0x1fda) & 0x08)) { }
• count = RREG8(MGAREG_VCOUNT) + 2;
• while (RREG8(MGAREG_VCOUNT) < count) { }
• return mga_crtc_do_set_base(crtc, old_fb, x, y, 0);

}

I do not really see why this code was lifter two functions up. Before is was deep in mga_set_start_address(), now it is in mga_crtc_mode_set_base(). Puzzeled?

Sam

-- 2.26.0