fix(drm): fall back only when KMS rejects the images, wait on lost master at resume

commit: 6c2aaa2bd42141e76eb94cd14d2f60f78a89e608
author: brice · 27d ago · 2026-09-25 17:33 UTC
parent: 1941387
signature: GPG VerifiedCD88F9E564E0102646FB6077A1A07C7C7C3E349D · arch-gpg Verified for the committer email

2 files · +20 -2

M internal/adapters/drm/output.go +19 -1


@@ -227,7 +227,12 @@ func (o *Output) Run(ctx context.Context, newRenderer func(w, h int) (ports.Rend
227	227		// Modeset on every enable: a fast disable+enable can coalesce to one true.
228	228		if on {
229	229		err := o.modeset()
230		-	if err != nil && !o.validated && o.kind < imagesDumb {
	230	+	if lostMaster(err) {
	231	+	// The seat took DRM master back: wait for the next enable.
	232	+	o.log.Warn().Err(err).Msg("resume")
	233	+	continue
	234	+	}
	235	+	if refused(err) && !o.validated && o.kind < imagesDumb {
231	236		o.log.Warn().Err(err).Str("connector", o.conn.name).Int("kind", int(o.kind)).Msg("modeset refused the output images")
232	237		o.freeImages()
233	238		err = o.showImages(r, o.kind+1, err)

@@ -386,6 +391,9 @@ func (o *Output) showImages(r ports.Renderer, kind imageKind, cause error) error
386	391		o.validated = true
387	392		return nil
388	393		}
	394	+	if !refused(err) {
	395	+	return err
	396	+	}
389	397		o.log.Warn().Err(err).Str("connector", o.conn.name).Int("kind", int(got)).Msg("modeset refused the output images")
390	398		o.freeImages()
391	399		if got == imagesDumb {

@@ -395,6 +403,16 @@ func (o *Output) showImages(r ports.Renderer, kind imageKind, cause error) error
395	403		}
396	404		}
397	405
	406	+	// refused reports a modeset error meaning KMS rejects the images.
	407	+	func refused(err error) bool {
	408	+	return errors.Is(err, unix.EINVAL) \|\| errors.Is(err, unix.ERANGE)
	409	+	}
	410	+
	411	+	// lostMaster reports a modeset error meaning the seat is switched away.
	412	+	func lostMaster(err error) bool {
	413	+	return errors.Is(err, unix.EACCES) \|\| errors.Is(err, unix.EPERM)
	414	+	}
	415	+
398	416		// setupImages gives the output the two images it flips between: renderer
399	417		// targets exported as dmabufs, or dumb buffers as a logged fallback. A
400	418		// kind that fails falls through to the next one.

 			// Modeset on every enable: a fast disable+enable can coalesce to one true.
 			if on {
 				err := o.modeset()
-				if err != nil && !o.validated && o.kind < imagesDumb {
+				if lostMaster(err) {
+					// The seat took DRM master back: wait for the next enable.
+					o.log.Warn().Err(err).Msg("resume")
+					continue
+				}
+				if refused(err) && !o.validated && o.kind < imagesDumb {
 					o.log.Warn().Err(err).Str("connector", o.conn.name).Int("kind", int(o.kind)).Msg("modeset refused the output images")
 					o.freeImages()
 					err = o.showImages(r, o.kind+1, err)
 			o.validated = true
 			return nil
 		}
+		if !refused(err) {
+			return err
+		}
 		o.log.Warn().Err(err).Str("connector", o.conn.name).Int("kind", int(got)).Msg("modeset refused the output images")
 		o.freeImages()
 		if got == imagesDumb {
 	}
 }
+// refused reports a modeset error meaning KMS rejects the images.
+func refused(err error) bool {
+	return errors.Is(err, unix.EINVAL) || errors.Is(err, unix.ERANGE)
+}
+// lostMaster reports a modeset error meaning the seat is switched away.
+func lostMaster(err error) bool {
+	return errors.Is(err, unix.EACCES) || errors.Is(err, unix.EPERM)
+}
 // setupImages gives the output the two images it flips between: renderer
 // targets exported as dmabufs, or dumb buffers as a logged fallback. A
 // kind that fails falls through to the next one.

M internal/adapters/vulkan/renderer.go +1 -1


@@ -745,13 +745,13 @@ func (r *Renderer) CopyBGRX(dst []byte, pitch int) {
745	745		}
746	746		}
747	747
748		-	// readback copies the last frame into the host buffer, once per frame.
749	748		// Missing from the bindings: VK_QUEUE_FAMILY_IGNORED, VK_WHOLE_SIZE.
750	749		const (
751	750		queueFamilyIgnored = ^uint32(0)
752	751		wholeSize = ^vk.DeviceSize(0)
753	752		)
754	753
	754	+	// readback copies the last frame into the host buffer, once per frame.
755	755		func (r *Renderer) readback() error {
756	756		if r.readBack \|\| r.last == nil \|\| r.last.image == 0 {
757	757		return nil

 	}
 }
-// readback copies the last frame into the host buffer, once per frame.
 // Missing from the bindings: VK_QUEUE_FAMILY_IGNORED, VK_WHOLE_SIZE.
 const (
 	queueFamilyIgnored = ^uint32(0)
 	wholeSize          = ^vk.DeviceSize(0)
 )
+// readback copies the last frame into the host buffer, once per frame.
 func (r *Renderer) readback() error {
 	if r.readBack || r.last == nil || r.last.image == 0 {
 		return nil