Hi Am 20.04.21 um 18:56 schrieb Takashi Iwai:
On bochs DRM driver, the execution of "setterm --blank force" results in a frozen screen instead of a blank screen. It's due to the lack of the screen blanking support in its code. Actually, the QEMU bochs vga side can switch to the blanking mode when the bit 0x20 is cleared on VGA_ATT_IW register (0x3c0), which updates ar_index in QEMU side. So, essentially, we'd just need to clear the bit at pipe disable callback; that's what this patch does essentially. However, a tricky part is that the QEMU vga code does treat VGA_ATT_IW register always as "flip-flop"; the first write is for index and the second write is for the data like palette. Meanwhile, in the current bochs DRM driver, the flip-flop wasn't considered, and it calls only the register update once with the value 0x20.
Unless bochs does things very different, the index should first be reset by reading 0x3da. Then write the index, then the data.
https://web.stanford.edu/class/cs140/projects/pintos/specs/freevga/vga/vgareg.htm#attribute Best regards Thomas
So, in this patch, we fix the behavior by simply writing the VGA_ATT_IW register value twice at each place as well. Signed-off-by: Takashi Iwai <tiwai@xxxxxxx> --- drivers/gpu/drm/bochs/bochs_hw.c | 13 ++++++++++++- drivers/gpu/drm/bochs/bochs_kms.c | 8 ++++++++ 2 files changed, 20 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/bochs/bochs_hw.c b/drivers/gpu/drm/bochs/bochs_hw.c index 2d7380a9890e..9a6f90216d6c 100644 --- a/drivers/gpu/drm/bochs/bochs_hw.c +++ b/drivers/gpu/drm/bochs/bochs_hw.c @@ -213,6 +213,14 @@ void bochs_hw_setmode(struct bochs_device *bochs, if (!drm_dev_enter(bochs->dev, &idx)) return;+ if (!mode) {+ DRM_DEBUG_DRIVER("crtc disabled\n"); + /* set to blank mode; send twice for ar_flip_flop */ + bochs_vga_writeb(bochs, 0x3c0, 0); + bochs_vga_writeb(bochs, 0x3c0, 0); + goto exit; + } + bochs->xres = mode->hdisplay; bochs->yres = mode->vdisplay; bochs->bpp = 32; @@ -223,7 +231,9 @@ void bochs_hw_setmode(struct bochs_device *bochs, bochs->xres, bochs->yres, bochs->bpp, bochs->yres_virtual);- bochs_vga_writeb(bochs, 0x3c0, 0x20); /* unblank */+ /* unblank; send twice for ar_flip_flop */ + bochs_vga_writeb(bochs, 0x3c0, 0x20); + bochs_vga_writeb(bochs, 0x3c0, 0x20);bochs_dispi_write(bochs, VBE_DISPI_INDEX_ENABLE, 0);bochs_dispi_write(bochs, VBE_DISPI_INDEX_BPP, bochs->bpp); @@ -239,6 +249,7 @@ void bochs_hw_setmode(struct bochs_device *bochs, bochs_dispi_write(bochs, VBE_DISPI_INDEX_ENABLE, VBE_DISPI_ENABLED | VBE_DISPI_LFB_ENABLED);+ exit:drm_dev_exit(idx); }diff --git a/drivers/gpu/drm/bochs/bochs_kms.c b/drivers/gpu/drm/bochs/bochs_kms.cindex 853081d186d5..b0d77d6d3ae4 100644 --- a/drivers/gpu/drm/bochs/bochs_kms.c +++ b/drivers/gpu/drm/bochs/bochs_kms.c @@ -57,6 +57,13 @@ static void bochs_pipe_enable(struct drm_simple_display_pipe *pipe, bochs_plane_update(bochs, plane_state); }+static void bochs_pipe_disable(struct drm_simple_display_pipe *pipe)+{ + struct bochs_device *bochs = pipe->crtc.dev->dev_private; + + bochs_hw_setmode(bochs, NULL); +} + static void bochs_pipe_update(struct drm_simple_display_pipe *pipe, struct drm_plane_state *old_state) { @@ -67,6 +74,7 @@ static void bochs_pipe_update(struct drm_simple_display_pipe *pipe,static const struct drm_simple_display_pipe_funcs bochs_pipe_funcs =
{
.enable = bochs_pipe_enable, + .disable = bochs_pipe_disable, .update = bochs_pipe_update, .prepare_fb = drm_gem_vram_simple_display_pipe_prepare_fb, .cleanup_fb = drm_gem_vram_simple_display_pipe_cleanup_fb,
-- Thomas Zimmermann Graphics Driver Developer SUSE Software Solutions Germany GmbH Maxfeldstr. 5, 90409 Nürnberg, Germany (HRB 36809, AG Nürnberg) Geschäftsführer: Felix Imendörffer
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