| Message ID | 20241119194038.530779-1-ian.forbes@broadcom.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | drm/vmwgfx: Add Fake EDID | expand |
Hi Am 19.11.24 um 20:40 schrieb Ian Forbes: > Most compositors are using a change in EDID as an indicator to > refresh their connector information on hotplug regardless of whether the > connector was previously connected. Originally the hotplug_mode_update > property was supposed to provide a hint to userspace to always refresh > connector info on hotplug as virtual devices such as vmwgfx and QXL > changed the connector without disconnecting it first. This was done to > implement Autofit. Unfortunately hotplug_mode_update was not widely > adopted and compositors used other heuristics to determine whether to > refresh the connector info. > > Currently a change in EDID is the one heuristic that seems to be universal. > No compositors currently implement hotplug_mode_update correctly or at all. > By implementing a fake EDID blob we can ensure that our EDID changes on > hotplug and therefore userspace will refresh the connector info so that > Autofit will work. This is the approach that virtio takes. > > This also removes the need to add hotplug_mode_update support for all > compositors as traditionally this niche feature has fallen on > virtualized driver developers to implement. Why don't you fix the compositors instead? I feel like NAK'ing this patch. The code itself is not so much a problem, but the commit message. Maybe it resolves problems with compositors, but it is a step backwards for the overall ecosystem. If the connector changes, your driver should increment the epoch counter. [1] That will send a hotplug event to userspace. The EDID alone does not say anything about connector status. Best regards Thomas [1] https://elixir.bootlin.com/linux/v6.11.8/source/include/drm/drm_connector.h#L1994 > > Signed-off-by: Ian Forbes <ian.forbes@broadcom.com> > --- > drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 172 ++++++++++++++++++++++++++- > drivers/gpu/drm/vmwgfx/vmwgfx_kms.h | 3 + > drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c | 2 + > 3 files changed, 176 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c > index 5a1192496d49..9d9d0b8539dd 100644 > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c > @@ -37,7 +37,6 @@ > #include <drm/drm_fourcc.h> > #include <drm/drm_rect.h> > #include <drm/drm_sysfs.h> > -#include <drm/drm_edid.h> > > void vmw_du_init(struct vmw_display_unit *du) > { > @@ -2662,6 +2661,175 @@ enum drm_mode_status vmw_connector_mode_valid(struct drm_connector *connector, > return MODE_OK; > } > > +/* > + * Average pixels per millimeter and centimeter for a circa 2020 display > + */ > +#define VMW_FAKE_PPMM 4 > +#define VMW_FAKE_PPCM 40 > + > +static void vmw_mode_to_timing(const struct drm_display_mode *mode, > + struct detailed_timing *timing) > +{ > + struct detailed_pixel_timing *dpt = &timing->data.pixel_data; > + > + const u8 hblank = (mode->htotal - mode->hdisplay); > + const u8 hfront = (mode->hsync_start - mode->hdisplay); > + const u8 hsync = (mode->hsync_end - mode->hsync_start); > + > + const u8 vblank = (mode->vtotal - mode->vdisplay); > + const u8 vfront = (mode->vsync_start - mode->vdisplay); > + const u8 vsync = (mode->vsync_end - mode->vsync_start); > + > + const unsigned int wmm = mode->hdisplay / VMW_FAKE_PPMM; > + const unsigned int hmm = mode->vdisplay / VMW_FAKE_PPMM; > + > + timing->pixel_clock = mode->clock / 10; > + memset(dpt, 0, sizeof(*dpt)); > + > + // horizontal > + dpt->hactive_lo = mode->hdisplay & 0xFF; > + dpt->hblank_lo = hblank & 0xFF; > + > + dpt->hactive_hblank_hi |= (mode->hdisplay >> 4) & 0xF0; > + dpt->hactive_hblank_hi |= (hblank >> 8) & 0x0F; > + > + dpt->hsync_offset_lo = hfront & 0xFF; > + dpt->hsync_pulse_width_lo = hsync & 0xFF; > + > + dpt->hsync_vsync_offset_pulse_width_hi |= (hfront >> 2) & 0xC0; > + dpt->hsync_vsync_offset_pulse_width_hi |= (hsync >> 4) & 0x30; > + > + // vertical > + dpt->vactive_lo = mode->vdisplay & 0xFF; > + dpt->vactive_vblank_hi |= (mode->vdisplay >> 4) & 0xF0; > + > + dpt->vblank_lo = vblank & 0xFF; > + dpt->vactive_vblank_hi |= (vblank >> 8) & 0x0F; > + > + dpt->vsync_offset_pulse_width_lo |= (vfront & 0x0F) << 4; > + dpt->vsync_offset_pulse_width_lo |= (vsync & 0x0F) << 0; > + > + dpt->hsync_vsync_offset_pulse_width_hi |= (vfront >> 4) & 0x0C; > + dpt->hsync_vsync_offset_pulse_width_hi |= (vsync >> 8) & 0x03; > + > + // physical sizes > + dpt->width_mm_lo = wmm & 0xFF; > + dpt->height_mm_lo = hmm & 0xFF; > + dpt->width_height_mm_hi |= (wmm >> 4) & 0xF0; > + dpt->width_height_mm_hi |= (hmm >> 8) & 0x0F; > + > + dpt->hborder = 0; > + dpt->vborder = 0; > + dpt->misc |= 0x18; > + dpt->misc |= (mode->flags & DRM_MODE_FLAG_PHSYNC) ? 0x2 : 0; > + dpt->misc |= (mode->flags & DRM_MODE_FLAG_PVSYNC) ? 0x4 : 0; > +} > + > +/* Our encoded Plug & Play ID > + * See: https://uefi.org/PNP_ACPI_Registry and https://uefi.org/PNP_ID_List > + */ > +static inline __be16 vmw_pnp_id(void) > +{ > + return cpu_to_be16((('V' - '@') << 10) | > + (('M' - '@') << 5) | > + (('W' - '@') << 0)); > +} > + > +/* > + * Fills in the fake EDID using the preferred mode. > + * See 'Vesa Enhanced EDID Standard Release A Revision 2' and > + * 'VESA DMT Standard Version 1.0 Revision 13'. > + */ > +static void vmw_fill_fake_edid(const struct drm_display_mode *pref_mode, > + unsigned int unit, struct edid *e) > +{ > + int checksum = 0; > + > + /* > + * Bump the manufacture week ever time we fill the edid so that > + * it will change on every hotplug. This way even if the screen > + * size does not change userspace will rescan the connector. A > + * hotplug with no changes in resolution is likely a multi-mon change > + * and the suggested_X/Y will have changed and we want userspace to > + * pick up this. Use this field to only fill the constant data once > + * by checking for zero. > + */ > + if (e->mfg_week++ == 0) { > + memset(e->header + 1, 0xFF, 6); > + > + e->product_id.manufacturer_name = vmw_pnp_id(); > + e->mfg_year = 32; // 2022 > + > + e->prod_code[0] = 'V'; > + e->prod_code[1] = 'M'; > + e->serial = 0xABC0 | unit; > + > + e->version = 1; > + e->revision = 4; > + > + e->input = 0xA0; > + e->gamma = 120; // 2.20 > + e->features = 0x26; > + > + // Standard sRGB color space > + e->red_green_lo = 0xEE; > + e->blue_white_lo = 0x91; > + e->red_x = 0xA3; > + e->red_y = 0x54; > + e->green_x = 0x4C; > + e->green_y = 0x99; > + e->blue_x = 0x26; > + e->blue_y = 0x0F; > + e->white_x = 0x50; > + e->white_y = 0x54; > + > + e->established_timings.t1 = 0x21; > + e->established_timings.t2 = 0x08; > + > + e->standard_timings[0].hsize = 0x81; > + e->standard_timings[0].vfreq_aspect = 0xC0; // 720p60 > + > + e->standard_timings[1].hsize = 0xD1; > + e->standard_timings[1].vfreq_aspect = 0xC0; // 1080p60 > + > + e->standard_timings[2].hsize = 0x81; > + e->standard_timings[2].vfreq_aspect = 0x80; // 1280x1024@60 > + > + e->standard_timings[3].hsize = 0xD1; > + e->standard_timings[3].vfreq_aspect = 0x40; // 1920x1440@60 > + > + e->standard_timings[4].hsize = 0xE1; > + e->standard_timings[4].vfreq_aspect = 0xC0; // 2048x1152@60 > + > + e->standard_timings[5].hsize = 0xA9; > + e->standard_timings[5].vfreq_aspect = 0x40; // 1600x1200@60 > + > + e->standard_timings[6].hsize = 0xB3; > + e->standard_timings[6].vfreq_aspect = 0x00; // 2048x1152@60 > + > + e->standard_timings[7].hsize = 0x95; > + e->standard_timings[7].vfreq_aspect = 0x00; // 1440x900@60 > + > + e->detailed_timings[1].data.other_data.type = EDID_DETAIL_MONITOR_NAME; > + memcpy(e->detailed_timings[1].data.other_data.data.str.str, > + "VMware Screen", 13); > + > + e->detailed_timings[2].data.other_data.type = 0x10; > + e->detailed_timings[3].data.other_data.type = 0x10; > + > + e->extensions = 0; > + } > + e->width_cm = DIV_ROUND_CLOSEST(pref_mode->hdisplay, VMW_FAKE_PPCM); > + e->height_cm = DIV_ROUND_CLOSEST(pref_mode->vdisplay, VMW_FAKE_PPCM); > + // This is the preferred/native mode > + vmw_mode_to_timing(pref_mode, &e->detailed_timings[0]); > + > + for (int i = 0; i < sizeof(struct edid) - 1; i++) > + checksum += ((u8 *)e)[i]; > + > + e->checksum = 0x100 - checksum; > +} > + > /* > * Common modes not present in the VESA DMT standard or assigned a VIC. > */ > @@ -2699,6 +2867,8 @@ int vmw_connector_get_modes(struct drm_connector *connector) > drm_mode_probed_add(connector, mode); > num_modes++; > drm_dbg_kms(dev, "preferred mode " DRM_MODE_FMT "\n", DRM_MODE_ARG(mode)); > + vmw_fill_fake_edid(mode, du->unit, &du->fake_edid); > + drm_connector_update_edid_property(connector, &du->fake_edid); > > /* Probe connector for all modes not exceeding our geom limits */ > max_width = dev_priv->texture_max_width; > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h > index 6a8bb60c507d..56c739d78582 100644 > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h > @@ -32,6 +32,7 @@ > #include <drm/drm_encoder.h> > #include <drm/drm_framebuffer.h> > #include <drm/drm_probe_helper.h> > +#include <drm/drm_edid.h> > > #include "vmwgfx_drv.h" > > @@ -363,6 +364,8 @@ struct vmw_display_unit { > unsigned pref_height; > bool pref_active; > > + struct edid fake_edid; > + > /* > * Gui positioning > */ > diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c > index 82d18b88f4a7..3defdf00a975 100644 > --- a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c > +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c > @@ -1631,6 +1631,8 @@ static int vmw_stdu_init(struct vmw_private *dev_priv, unsigned unit) > drm_object_attach_property(&connector->base, > dev->mode_config.suggested_y_property, 0); > > + drm_connector_attach_edid_property(connector); > + > vmw_du_init(&stdu->base); > > return 0;
On Wed, 20 Nov 2024, Thomas Zimmermann <tzimmermann@suse.de> wrote: > Hi > > > Am 19.11.24 um 20:40 schrieb Ian Forbes: >> Most compositors are using a change in EDID as an indicator to >> refresh their connector information on hotplug regardless of whether the >> connector was previously connected. Originally the hotplug_mode_update >> property was supposed to provide a hint to userspace to always refresh >> connector info on hotplug as virtual devices such as vmwgfx and QXL >> changed the connector without disconnecting it first. This was done to >> implement Autofit. Unfortunately hotplug_mode_update was not widely >> adopted and compositors used other heuristics to determine whether to >> refresh the connector info. >> >> Currently a change in EDID is the one heuristic that seems to be universal. >> No compositors currently implement hotplug_mode_update correctly or at all. >> By implementing a fake EDID blob we can ensure that our EDID changes on >> hotplug and therefore userspace will refresh the connector info so that >> Autofit will work. This is the approach that virtio takes. >> >> This also removes the need to add hotplug_mode_update support for all >> compositors as traditionally this niche feature has fallen on >> virtualized driver developers to implement. > > Why don't you fix the compositors instead? > > I feel like NAK'ing this patch. The code itself is not so much a > problem, but the commit message. Oh, I think the code is problematic too. Please avoid all struct edid based interfaces, in this case drm_connector_update_edid_property(). They will be removed in the future, and adding more is counter-productive. Everything should be struct drm_edid based going forward. Of course, actually grafting the EDID needs struct edid. And that's kind of annoying too. Do we really want to spread the EDID details all over the place? This one combines drm_edid.h structs and magic numbers in a jumble. I'm kind of hoping we'd get rid of driver usage of struct edid, though that's a long road. But we've made a lot of progress towards it, there aren't that many places left that directly look at the guts of EDID, and most of it is centralized in drm_edid.c. Of course, not using the standard drm_edid_read* interfaces also lacks on features such as providing the EDID via the firmware loader or debugfs, which can be handy for testing and debugging, but that's a minor issue. > Maybe it resolves problems with > compositors, but it is a step backwards for the overall ecosystem. If > the connector changes, your driver should increment the epoch counter. > [1] That will send a hotplug event to userspace. The EDID alone does not > say anything about connector status. Yeah, unplugging and replugging the same display with the same EDID isn't a problem for other drivers, and they don't have to do this kind of stuff to trick userspace. Maybe vmwgfx should handle (or simulate) hotplugs better? And preferrably let the EDID functions handle epoch counter updates instead of doing it yourself, if at all possible. BR, Jani. > > Best regards > Thomas > > [1] > https://elixir.bootlin.com/linux/v6.11.8/source/include/drm/drm_connector.h#L1994 > > > >> >> Signed-off-by: Ian Forbes <ian.forbes@broadcom.com> >> --- >> drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 172 ++++++++++++++++++++++++++- >> drivers/gpu/drm/vmwgfx/vmwgfx_kms.h | 3 + >> drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c | 2 + >> 3 files changed, 176 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c >> index 5a1192496d49..9d9d0b8539dd 100644 >> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c >> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c >> @@ -37,7 +37,6 @@ >> #include <drm/drm_fourcc.h> >> #include <drm/drm_rect.h> >> #include <drm/drm_sysfs.h> >> -#include <drm/drm_edid.h> >> >> void vmw_du_init(struct vmw_display_unit *du) >> { >> @@ -2662,6 +2661,175 @@ enum drm_mode_status vmw_connector_mode_valid(struct drm_connector *connector, >> return MODE_OK; >> } >> >> +/* >> + * Average pixels per millimeter and centimeter for a circa 2020 display >> + */ >> +#define VMW_FAKE_PPMM 4 >> +#define VMW_FAKE_PPCM 40 >> + >> +static void vmw_mode_to_timing(const struct drm_display_mode *mode, >> + struct detailed_timing *timing) >> +{ >> + struct detailed_pixel_timing *dpt = &timing->data.pixel_data; >> + >> + const u8 hblank = (mode->htotal - mode->hdisplay); >> + const u8 hfront = (mode->hsync_start - mode->hdisplay); >> + const u8 hsync = (mode->hsync_end - mode->hsync_start); >> + >> + const u8 vblank = (mode->vtotal - mode->vdisplay); >> + const u8 vfront = (mode->vsync_start - mode->vdisplay); >> + const u8 vsync = (mode->vsync_end - mode->vsync_start); >> + >> + const unsigned int wmm = mode->hdisplay / VMW_FAKE_PPMM; >> + const unsigned int hmm = mode->vdisplay / VMW_FAKE_PPMM; >> + >> + timing->pixel_clock = mode->clock / 10; >> + memset(dpt, 0, sizeof(*dpt)); >> + >> + // horizontal >> + dpt->hactive_lo = mode->hdisplay & 0xFF; >> + dpt->hblank_lo = hblank & 0xFF; >> + >> + dpt->hactive_hblank_hi |= (mode->hdisplay >> 4) & 0xF0; >> + dpt->hactive_hblank_hi |= (hblank >> 8) & 0x0F; >> + >> + dpt->hsync_offset_lo = hfront & 0xFF; >> + dpt->hsync_pulse_width_lo = hsync & 0xFF; >> + >> + dpt->hsync_vsync_offset_pulse_width_hi |= (hfront >> 2) & 0xC0; >> + dpt->hsync_vsync_offset_pulse_width_hi |= (hsync >> 4) & 0x30; >> + >> + // vertical >> + dpt->vactive_lo = mode->vdisplay & 0xFF; >> + dpt->vactive_vblank_hi |= (mode->vdisplay >> 4) & 0xF0; >> + >> + dpt->vblank_lo = vblank & 0xFF; >> + dpt->vactive_vblank_hi |= (vblank >> 8) & 0x0F; >> + >> + dpt->vsync_offset_pulse_width_lo |= (vfront & 0x0F) << 4; >> + dpt->vsync_offset_pulse_width_lo |= (vsync & 0x0F) << 0; >> + >> + dpt->hsync_vsync_offset_pulse_width_hi |= (vfront >> 4) & 0x0C; >> + dpt->hsync_vsync_offset_pulse_width_hi |= (vsync >> 8) & 0x03; >> + >> + // physical sizes >> + dpt->width_mm_lo = wmm & 0xFF; >> + dpt->height_mm_lo = hmm & 0xFF; >> + dpt->width_height_mm_hi |= (wmm >> 4) & 0xF0; >> + dpt->width_height_mm_hi |= (hmm >> 8) & 0x0F; >> + >> + dpt->hborder = 0; >> + dpt->vborder = 0; >> + dpt->misc |= 0x18; >> + dpt->misc |= (mode->flags & DRM_MODE_FLAG_PHSYNC) ? 0x2 : 0; >> + dpt->misc |= (mode->flags & DRM_MODE_FLAG_PVSYNC) ? 0x4 : 0; >> +} >> + >> +/* Our encoded Plug & Play ID >> + * See: https://uefi.org/PNP_ACPI_Registry and https://uefi.org/PNP_ID_List >> + */ >> +static inline __be16 vmw_pnp_id(void) >> +{ >> + return cpu_to_be16((('V' - '@') << 10) | >> + (('M' - '@') << 5) | >> + (('W' - '@') << 0)); >> +} >> + >> +/* >> + * Fills in the fake EDID using the preferred mode. >> + * See 'Vesa Enhanced EDID Standard Release A Revision 2' and >> + * 'VESA DMT Standard Version 1.0 Revision 13'. >> + */ >> +static void vmw_fill_fake_edid(const struct drm_display_mode *pref_mode, >> + unsigned int unit, struct edid *e) >> +{ >> + int checksum = 0; >> + >> + /* >> + * Bump the manufacture week ever time we fill the edid so that >> + * it will change on every hotplug. This way even if the screen >> + * size does not change userspace will rescan the connector. A >> + * hotplug with no changes in resolution is likely a multi-mon change >> + * and the suggested_X/Y will have changed and we want userspace to >> + * pick up this. Use this field to only fill the constant data once >> + * by checking for zero. >> + */ >> + if (e->mfg_week++ == 0) { >> + memset(e->header + 1, 0xFF, 6); >> + >> + e->product_id.manufacturer_name = vmw_pnp_id(); >> + e->mfg_year = 32; // 2022 >> + >> + e->prod_code[0] = 'V'; >> + e->prod_code[1] = 'M'; >> + e->serial = 0xABC0 | unit; >> + >> + e->version = 1; >> + e->revision = 4; >> + >> + e->input = 0xA0; >> + e->gamma = 120; // 2.20 >> + e->features = 0x26; >> + >> + // Standard sRGB color space >> + e->red_green_lo = 0xEE; >> + e->blue_white_lo = 0x91; >> + e->red_x = 0xA3; >> + e->red_y = 0x54; >> + e->green_x = 0x4C; >> + e->green_y = 0x99; >> + e->blue_x = 0x26; >> + e->blue_y = 0x0F; >> + e->white_x = 0x50; >> + e->white_y = 0x54; >> + >> + e->established_timings.t1 = 0x21; >> + e->established_timings.t2 = 0x08; >> + >> + e->standard_timings[0].hsize = 0x81; >> + e->standard_timings[0].vfreq_aspect = 0xC0; // 720p60 >> + >> + e->standard_timings[1].hsize = 0xD1; >> + e->standard_timings[1].vfreq_aspect = 0xC0; // 1080p60 >> + >> + e->standard_timings[2].hsize = 0x81; >> + e->standard_timings[2].vfreq_aspect = 0x80; // 1280x1024@60 >> + >> + e->standard_timings[3].hsize = 0xD1; >> + e->standard_timings[3].vfreq_aspect = 0x40; // 1920x1440@60 >> + >> + e->standard_timings[4].hsize = 0xE1; >> + e->standard_timings[4].vfreq_aspect = 0xC0; // 2048x1152@60 >> + >> + e->standard_timings[5].hsize = 0xA9; >> + e->standard_timings[5].vfreq_aspect = 0x40; // 1600x1200@60 >> + >> + e->standard_timings[6].hsize = 0xB3; >> + e->standard_timings[6].vfreq_aspect = 0x00; // 2048x1152@60 >> + >> + e->standard_timings[7].hsize = 0x95; >> + e->standard_timings[7].vfreq_aspect = 0x00; // 1440x900@60 >> + >> + e->detailed_timings[1].data.other_data.type = EDID_DETAIL_MONITOR_NAME; >> + memcpy(e->detailed_timings[1].data.other_data.data.str.str, >> + "VMware Screen", 13); >> + >> + e->detailed_timings[2].data.other_data.type = 0x10; >> + e->detailed_timings[3].data.other_data.type = 0x10; >> + >> + e->extensions = 0; >> + } >> + e->width_cm = DIV_ROUND_CLOSEST(pref_mode->hdisplay, VMW_FAKE_PPCM); >> + e->height_cm = DIV_ROUND_CLOSEST(pref_mode->vdisplay, VMW_FAKE_PPCM); >> + // This is the preferred/native mode >> + vmw_mode_to_timing(pref_mode, &e->detailed_timings[0]); >> + >> + for (int i = 0; i < sizeof(struct edid) - 1; i++) >> + checksum += ((u8 *)e)[i]; >> + >> + e->checksum = 0x100 - checksum; >> +} >> + >> /* >> * Common modes not present in the VESA DMT standard or assigned a VIC. >> */ >> @@ -2699,6 +2867,8 @@ int vmw_connector_get_modes(struct drm_connector *connector) >> drm_mode_probed_add(connector, mode); >> num_modes++; >> drm_dbg_kms(dev, "preferred mode " DRM_MODE_FMT "\n", DRM_MODE_ARG(mode)); >> + vmw_fill_fake_edid(mode, du->unit, &du->fake_edid); >> + drm_connector_update_edid_property(connector, &du->fake_edid); >> >> /* Probe connector for all modes not exceeding our geom limits */ >> max_width = dev_priv->texture_max_width; >> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h >> index 6a8bb60c507d..56c739d78582 100644 >> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h >> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h >> @@ -32,6 +32,7 @@ >> #include <drm/drm_encoder.h> >> #include <drm/drm_framebuffer.h> >> #include <drm/drm_probe_helper.h> >> +#include <drm/drm_edid.h> >> >> #include "vmwgfx_drv.h" >> >> @@ -363,6 +364,8 @@ struct vmw_display_unit { >> unsigned pref_height; >> bool pref_active; >> >> + struct edid fake_edid; >> + >> /* >> * Gui positioning >> */ >> diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c >> index 82d18b88f4a7..3defdf00a975 100644 >> --- a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c >> +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c >> @@ -1631,6 +1631,8 @@ static int vmw_stdu_init(struct vmw_private *dev_priv, unsigned unit) >> drm_object_attach_property(&connector->base, >> dev->mode_config.suggested_y_property, 0); >> >> + drm_connector_attach_edid_property(connector); >> + >> vmw_du_init(&stdu->base); >> >> return 0;
On Wed, Nov 20, 2024 at 5:22 AM Jani Nikula <jani.nikula@linux.intel.com> wrote: > > On Wed, 20 Nov 2024, Thomas Zimmermann <tzimmermann@suse.de> wrote: > > Hi > > > > > > Am 19.11.24 um 20:40 schrieb Ian Forbes: > >> Most compositors are using a change in EDID as an indicator to > >> refresh their connector information on hotplug regardless of whether the > >> connector was previously connected. Originally the hotplug_mode_update > >> property was supposed to provide a hint to userspace to always refresh > >> connector info on hotplug as virtual devices such as vmwgfx and QXL > >> changed the connector without disconnecting it first. This was done to > >> implement Autofit. Unfortunately hotplug_mode_update was not widely > >> adopted and compositors used other heuristics to determine whether to > >> refresh the connector info. > >> > >> Currently a change in EDID is the one heuristic that seems to be universal. > >> No compositors currently implement hotplug_mode_update correctly or at all. > >> By implementing a fake EDID blob we can ensure that our EDID changes on > >> hotplug and therefore userspace will refresh the connector info so that > >> Autofit will work. This is the approach that virtio takes. > >> > >> This also removes the need to add hotplug_mode_update support for all > >> compositors as traditionally this niche feature has fallen on > >> virtualized driver developers to implement. > > > > Why don't you fix the compositors instead? > > > > I feel like NAK'ing this patch. The code itself is not so much a > > problem, but the commit message. > > Oh, I think the code is problematic too. > > Please avoid all struct edid based interfaces, in this case > drm_connector_update_edid_property(). They will be removed in the > future, and adding more is counter-productive. Everything should be > struct drm_edid based going forward. > > Of course, actually grafting the EDID needs struct edid. And that's kind > of annoying too. Do we really want to spread the EDID details all over > the place? This one combines drm_edid.h structs and magic numbers in a > jumble. I'm kind of hoping we'd get rid of driver usage of struct edid, > though that's a long road. But we've made a lot of progress towards it, > there aren't that many places left that directly look at the guts of > EDID, and most of it is centralized in drm_edid.c. > > Of course, not using the standard drm_edid_read* interfaces also lacks > on features such as providing the EDID via the firmware loader or > debugfs, which can be handy for testing and debugging, but that's a > minor issue. > > > Maybe it resolves problems with > > compositors, but it is a step backwards for the overall ecosystem. If > > the connector changes, your driver should increment the epoch counter. > > [1] That will send a hotplug event to userspace. The EDID alone does not > > say anything about connector status. > > Yeah, unplugging and replugging the same display with the same EDID > isn't a problem for other drivers, and they don't have to do this kind > of stuff to trick userspace. Maybe vmwgfx should handle (or simulate) > hotplugs better? I don't think that's what Ian is trying to fix. There's two different issues: 1) The code using struct edid which is frowned upon. 2) The virtualized drivers not behaving like real GPU's and thus breaking userspace. vmwgfx and qxl do not provide edid at all. It's null. But every time someone resizes a host side window in which the para-virtualized driver is displaying, the preferred mode changes. Userspace kept checking whether the edid changes on each hotplug event to figure out if it got new modes and refresh if it noticed that edid changed. Because on qxl and vmwgfx the edid never changes (it's always null) Dave added hotplug_mode_update property which only qxl and vmwgfx send and its presence indicates that the userspace should refresh modes even if edid didn't change. Because that property is only used by qxl and vmwgfx everyone gets it wrong. The property was specifically added to fix gnome and Ian noticed that currently even gnome is broken: https://gitlab.gnome.org/GNOME/mutter/-/blob/main/src/backends/native/meta-kms-connector.c#L940 hotplug_mode_update doesn't change, it's just a flag that indicates that userspace needs a full mode rescan. virtiogpu deals with it by providing a fake edid hostside and not using hotplug_mode_update. So there are two different arguments to be made with this patch: 1) "You should provide the fake edid hostside like virtiogpu". But that means that we'd still be using the broken hotplug_mode_update on everything that's been released. 2) "You should fix all of userspace". Which is not realistic because vast majority of people are not running on qxl or vmwgfx so basically everyone either doesn't support hotplug_mode_update at all (e.g. kwin, window maker, weston) or they handle it incorrectly (e.g. mutter). It's not terribly realistic to be monitoring every compositor out there for breaking changes. I don't love the code and I'm not excited about putting this in the driver, but also I don't see a better way of fixing the core issue (which is that some virtualized drivers just do not behave like real gpu's). z
On Wed, Nov 20, 2024 at 4:22 AM Jani Nikula <jani.nikula@linux.intel.com> wrote: > > Please avoid all struct edid based interfaces, in this case > drm_connector_update_edid_property(). They will be removed in the > future, and adding more is counter-productive. Everything should be > struct drm_edid based going forward. > > Of course, actually grafting the EDID needs struct edid. And that's kind > of annoying too. Do we really want to spread the EDID details all over > the place? This one combines drm_edid.h structs and magic numbers in a > jumble. I'm kind of hoping we'd get rid of driver usage of struct edid, > though that's a long road. But we've made a lot of progress towards it, > there aren't that many places left that directly look at the guts of > EDID, and most of it is centralized in drm_edid.c. > drm_edid isn't exported so we can't use it. I know you've read the EDID spec so complaining about the magic numbers is silly. I didn't choose to make the whole spec based on bizarrely packed 10 and 12 bit numbers, they are unavoidable. > > > Maybe it resolves problems with > > compositors, but it is a step backwards for the overall ecosystem. If > > the connector changes, your driver should increment the epoch counter. > > [1] That will send a hotplug event to userspace. The EDID alone does not > > say anything about connector status. > > Yeah, unplugging and replugging the same display with the same EDID > isn't a problem for other drivers, and they don't have to do this kind > of stuff to trick userspace. Maybe vmwgfx should handle (or simulate) > hotplugs better? > > And preferrably let the EDID functions handle epoch counter updates > instead of doing it yourself, if at all possible. > > BR, > Jani. > You're both missing the fact that virtual devices never disconnect active displays. We don't have to do a disconnect/connect cycle like a physical monitor and we wouldn't want to because it would be poor user experience. The issue is not sending the hotplug event, it's that userspace will ignore hotplug events on connectors that were previously connected because they assume a disconnect/connect cycle must occur for changes to occur. The whole point of hotplug_mode_update was as a hint to userspace that the display can be "re-plugged" without a disconnect first and to always rescan the connector for changes on hotplug. Currently compositors are taking an arbitrary set of connector properties that they've organically collected over the years and doing a diff to trigger a refresh in the modes/display layout. EDID is the only property that they universally agree should trigger a display layout change. The fact that Autofit works on any compsitors using vmwgfx, qxl, or virtio is completely by accident. EDID is also a standardized connector property so it's not really fair to say that all devices should export this property and then when we fix our deficiency to block it. Now that it's standardized it is part of the uapi and if userspace does weird things with it it's not really our concern. The fact that it's standardized is also likely the reason it is being used in such a fashion. Ian,
diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c index 5a1192496d49..9d9d0b8539dd 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.c @@ -37,7 +37,6 @@ #include <drm/drm_fourcc.h> #include <drm/drm_rect.h> #include <drm/drm_sysfs.h> -#include <drm/drm_edid.h> void vmw_du_init(struct vmw_display_unit *du) { @@ -2662,6 +2661,175 @@ enum drm_mode_status vmw_connector_mode_valid(struct drm_connector *connector, return MODE_OK; } +/* + * Average pixels per millimeter and centimeter for a circa 2020 display + */ +#define VMW_FAKE_PPMM 4 +#define VMW_FAKE_PPCM 40 + +static void vmw_mode_to_timing(const struct drm_display_mode *mode, + struct detailed_timing *timing) +{ + struct detailed_pixel_timing *dpt = &timing->data.pixel_data; + + const u8 hblank = (mode->htotal - mode->hdisplay); + const u8 hfront = (mode->hsync_start - mode->hdisplay); + const u8 hsync = (mode->hsync_end - mode->hsync_start); + + const u8 vblank = (mode->vtotal - mode->vdisplay); + const u8 vfront = (mode->vsync_start - mode->vdisplay); + const u8 vsync = (mode->vsync_end - mode->vsync_start); + + const unsigned int wmm = mode->hdisplay / VMW_FAKE_PPMM; + const unsigned int hmm = mode->vdisplay / VMW_FAKE_PPMM; + + timing->pixel_clock = mode->clock / 10; + memset(dpt, 0, sizeof(*dpt)); + + // horizontal + dpt->hactive_lo = mode->hdisplay & 0xFF; + dpt->hblank_lo = hblank & 0xFF; + + dpt->hactive_hblank_hi |= (mode->hdisplay >> 4) & 0xF0; + dpt->hactive_hblank_hi |= (hblank >> 8) & 0x0F; + + dpt->hsync_offset_lo = hfront & 0xFF; + dpt->hsync_pulse_width_lo = hsync & 0xFF; + + dpt->hsync_vsync_offset_pulse_width_hi |= (hfront >> 2) & 0xC0; + dpt->hsync_vsync_offset_pulse_width_hi |= (hsync >> 4) & 0x30; + + // vertical + dpt->vactive_lo = mode->vdisplay & 0xFF; + dpt->vactive_vblank_hi |= (mode->vdisplay >> 4) & 0xF0; + + dpt->vblank_lo = vblank & 0xFF; + dpt->vactive_vblank_hi |= (vblank >> 8) & 0x0F; + + dpt->vsync_offset_pulse_width_lo |= (vfront & 0x0F) << 4; + dpt->vsync_offset_pulse_width_lo |= (vsync & 0x0F) << 0; + + dpt->hsync_vsync_offset_pulse_width_hi |= (vfront >> 4) & 0x0C; + dpt->hsync_vsync_offset_pulse_width_hi |= (vsync >> 8) & 0x03; + + // physical sizes + dpt->width_mm_lo = wmm & 0xFF; + dpt->height_mm_lo = hmm & 0xFF; + dpt->width_height_mm_hi |= (wmm >> 4) & 0xF0; + dpt->width_height_mm_hi |= (hmm >> 8) & 0x0F; + + dpt->hborder = 0; + dpt->vborder = 0; + dpt->misc |= 0x18; + dpt->misc |= (mode->flags & DRM_MODE_FLAG_PHSYNC) ? 0x2 : 0; + dpt->misc |= (mode->flags & DRM_MODE_FLAG_PVSYNC) ? 0x4 : 0; +} + +/* Our encoded Plug & Play ID + * See: https://uefi.org/PNP_ACPI_Registry and https://uefi.org/PNP_ID_List + */ +static inline __be16 vmw_pnp_id(void) +{ + return cpu_to_be16((('V' - '@') << 10) | + (('M' - '@') << 5) | + (('W' - '@') << 0)); +} + +/* + * Fills in the fake EDID using the preferred mode. + * See 'Vesa Enhanced EDID Standard Release A Revision 2' and + * 'VESA DMT Standard Version 1.0 Revision 13'. + */ +static void vmw_fill_fake_edid(const struct drm_display_mode *pref_mode, + unsigned int unit, struct edid *e) +{ + int checksum = 0; + + /* + * Bump the manufacture week ever time we fill the edid so that + * it will change on every hotplug. This way even if the screen + * size does not change userspace will rescan the connector. A + * hotplug with no changes in resolution is likely a multi-mon change + * and the suggested_X/Y will have changed and we want userspace to + * pick up this. Use this field to only fill the constant data once + * by checking for zero. + */ + if (e->mfg_week++ == 0) { + memset(e->header + 1, 0xFF, 6); + + e->product_id.manufacturer_name = vmw_pnp_id(); + e->mfg_year = 32; // 2022 + + e->prod_code[0] = 'V'; + e->prod_code[1] = 'M'; + e->serial = 0xABC0 | unit; + + e->version = 1; + e->revision = 4; + + e->input = 0xA0; + e->gamma = 120; // 2.20 + e->features = 0x26; + + // Standard sRGB color space + e->red_green_lo = 0xEE; + e->blue_white_lo = 0x91; + e->red_x = 0xA3; + e->red_y = 0x54; + e->green_x = 0x4C; + e->green_y = 0x99; + e->blue_x = 0x26; + e->blue_y = 0x0F; + e->white_x = 0x50; + e->white_y = 0x54; + + e->established_timings.t1 = 0x21; + e->established_timings.t2 = 0x08; + + e->standard_timings[0].hsize = 0x81; + e->standard_timings[0].vfreq_aspect = 0xC0; // 720p60 + + e->standard_timings[1].hsize = 0xD1; + e->standard_timings[1].vfreq_aspect = 0xC0; // 1080p60 + + e->standard_timings[2].hsize = 0x81; + e->standard_timings[2].vfreq_aspect = 0x80; // 1280x1024@60 + + e->standard_timings[3].hsize = 0xD1; + e->standard_timings[3].vfreq_aspect = 0x40; // 1920x1440@60 + + e->standard_timings[4].hsize = 0xE1; + e->standard_timings[4].vfreq_aspect = 0xC0; // 2048x1152@60 + + e->standard_timings[5].hsize = 0xA9; + e->standard_timings[5].vfreq_aspect = 0x40; // 1600x1200@60 + + e->standard_timings[6].hsize = 0xB3; + e->standard_timings[6].vfreq_aspect = 0x00; // 2048x1152@60 + + e->standard_timings[7].hsize = 0x95; + e->standard_timings[7].vfreq_aspect = 0x00; // 1440x900@60 + + e->detailed_timings[1].data.other_data.type = EDID_DETAIL_MONITOR_NAME; + memcpy(e->detailed_timings[1].data.other_data.data.str.str, + "VMware Screen", 13); + + e->detailed_timings[2].data.other_data.type = 0x10; + e->detailed_timings[3].data.other_data.type = 0x10; + + e->extensions = 0; + } + e->width_cm = DIV_ROUND_CLOSEST(pref_mode->hdisplay, VMW_FAKE_PPCM); + e->height_cm = DIV_ROUND_CLOSEST(pref_mode->vdisplay, VMW_FAKE_PPCM); + // This is the preferred/native mode + vmw_mode_to_timing(pref_mode, &e->detailed_timings[0]); + + for (int i = 0; i < sizeof(struct edid) - 1; i++) + checksum += ((u8 *)e)[i]; + + e->checksum = 0x100 - checksum; +} + /* * Common modes not present in the VESA DMT standard or assigned a VIC. */ @@ -2699,6 +2867,8 @@ int vmw_connector_get_modes(struct drm_connector *connector) drm_mode_probed_add(connector, mode); num_modes++; drm_dbg_kms(dev, "preferred mode " DRM_MODE_FMT "\n", DRM_MODE_ARG(mode)); + vmw_fill_fake_edid(mode, du->unit, &du->fake_edid); + drm_connector_update_edid_property(connector, &du->fake_edid); /* Probe connector for all modes not exceeding our geom limits */ max_width = dev_priv->texture_max_width; diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h index 6a8bb60c507d..56c739d78582 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_kms.h @@ -32,6 +32,7 @@ #include <drm/drm_encoder.h> #include <drm/drm_framebuffer.h> #include <drm/drm_probe_helper.h> +#include <drm/drm_edid.h> #include "vmwgfx_drv.h" @@ -363,6 +364,8 @@ struct vmw_display_unit { unsigned pref_height; bool pref_active; + struct edid fake_edid; + /* * Gui positioning */ diff --git a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c index 82d18b88f4a7..3defdf00a975 100644 --- a/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c +++ b/drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c @@ -1631,6 +1631,8 @@ static int vmw_stdu_init(struct vmw_private *dev_priv, unsigned unit) drm_object_attach_property(&connector->base, dev->mode_config.suggested_y_property, 0); + drm_connector_attach_edid_property(connector); + vmw_du_init(&stdu->base); return 0;
Most compositors are using a change in EDID as an indicator to refresh their connector information on hotplug regardless of whether the connector was previously connected. Originally the hotplug_mode_update property was supposed to provide a hint to userspace to always refresh connector info on hotplug as virtual devices such as vmwgfx and QXL changed the connector without disconnecting it first. This was done to implement Autofit. Unfortunately hotplug_mode_update was not widely adopted and compositors used other heuristics to determine whether to refresh the connector info. Currently a change in EDID is the one heuristic that seems to be universal. No compositors currently implement hotplug_mode_update correctly or at all. By implementing a fake EDID blob we can ensure that our EDID changes on hotplug and therefore userspace will refresh the connector info so that Autofit will work. This is the approach that virtio takes. This also removes the need to add hotplug_mode_update support for all compositors as traditionally this niche feature has fallen on virtualized driver developers to implement. Signed-off-by: Ian Forbes <ian.forbes@broadcom.com> --- drivers/gpu/drm/vmwgfx/vmwgfx_kms.c | 172 ++++++++++++++++++++++++++- drivers/gpu/drm/vmwgfx/vmwgfx_kms.h | 3 + drivers/gpu/drm/vmwgfx/vmwgfx_stdu.c | 2 + 3 files changed, 176 insertions(+), 1 deletion(-)