| Message ID | 20230529130028.2193945-1-jouni.hogander@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/i915: Use 18 fast wake fast wake AUX sync len | expand |
> -----Original Message----- > From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf Of Jouni > Högander > Sent: Monday, May 29, 2023 6:30 PM > To: intel-gfx@lists.freedesktop.org > Subject: [Intel-gfx] [PATCH] drm/i915: Use 18 fast wake fast wake AUX sync > len > > HW default for wake sync pulses is 18. 10 precarge and 8 preamble. There is > no reason to change this especially as it is causing problems with certain eDP > panels. > > Signed-off-by: Jouni Högander <jouni.hogander@intel.com> > Fixes: 605f7c731333 ("drm/i915: Fix fast wake AUX sync len") > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8475 > --- > drivers/gpu/drm/i915/display/intel_dp_aux.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c > b/drivers/gpu/drm/i915/display/intel_dp_aux.c > index 0c27db8ae4f1..197c6e81db14 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c > @@ -129,7 +129,7 @@ static int intel_dp_aux_sync_len(void) > > static int intel_dp_aux_fw_sync_len(void) { > - int precharge = 16; /* 10-16 */ > + int precharge = 10; /* 10-16 */ Is this change required in intel_dp_aux_sync_len() as well? Thanks and Regards, Arun R Murthy -------------------- > int preamble = 8; > > return precharge + preamble; > -- > 2.34.1
On Mon, 29 May 2023, Jouni Högander <jouni.hogander@intel.com> wrote: > HW default for wake sync pulses is 18. 10 precarge and 8 preamble. There is > no reason to change this especially as it is causing problems with certain > eDP panels. > > Signed-off-by: Jouni Högander <jouni.hogander@intel.com> > Fixes: 605f7c731333 ("drm/i915: Fix fast wake AUX sync len") Due to the cherry-picks I think it's better to reference e1c71f8f9180 ("drm/i915: Fix fast wake AUX sync len") which has been backported to stable. We need this fix to go wherever that's been backported. What happens if we use cc: stable and this gets backported to a kernel that does *not* have "drm/i915: Fix fast wake AUX sync len"? Any harm in that? BR, Jani. > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8475 > --- > drivers/gpu/drm/i915/display/intel_dp_aux.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c > index 0c27db8ae4f1..197c6e81db14 100644 > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c > @@ -129,7 +129,7 @@ static int intel_dp_aux_sync_len(void) > > static int intel_dp_aux_fw_sync_len(void) > { > - int precharge = 16; /* 10-16 */ > + int precharge = 10; /* 10-16 */ > int preamble = 8; > > return precharge + preamble;
On Tue, 2023-05-30 at 09:06 +0000, Murthy, Arun R wrote: > > -----Original Message----- > > From: Intel-gfx <intel-gfx-bounces@lists.freedesktop.org> On Behalf > > Of Jouni > > Högander > > Sent: Monday, May 29, 2023 6:30 PM > > To: intel-gfx@lists.freedesktop.org > > Subject: [Intel-gfx] [PATCH] drm/i915: Use 18 fast wake fast wake > > AUX sync > > len > > > > HW default for wake sync pulses is 18. 10 precarge and 8 preamble. > > There is > > no reason to change this especially as it is causing problems with > > certain eDP > > panels. > > > > Signed-off-by: Jouni Högander <jouni.hogander@intel.com> > > Fixes: 605f7c731333 ("drm/i915: Fix fast wake AUX sync len") > > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8475 > > --- > > drivers/gpu/drm/i915/display/intel_dp_aux.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c > > b/drivers/gpu/drm/i915/display/intel_dp_aux.c > > index 0c27db8ae4f1..197c6e81db14 100644 > > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c > > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c > > @@ -129,7 +129,7 @@ static int intel_dp_aux_sync_len(void) > > > > static int intel_dp_aux_fw_sync_len(void) { > > - int precharge = 16; /* 10-16 */ > > + int precharge = 10; /* 10-16 */ > > Is this change required in intel_dp_aux_sync_len() as well? That is a good question. The issue is triggered with certain PSR panels and only fast wake sync len impacts PSR sequence -> definetely it's not in scope of this patch. BR, Jouni Högander > > Thanks and Regards, > Arun R Murthy > -------------------- > > > int preamble = 8; > > > > return precharge + preamble; > > -- > > 2.34.1 >
On Tue, 2023-05-30 at 12:14 +0300, Jani Nikula wrote: > On Mon, 29 May 2023, Jouni Högander <jouni.hogander@intel.com> wrote: > > HW default for wake sync pulses is 18. 10 precarge and 8 preamble. > > There is > > no reason to change this especially as it is causing problems with > > certain > > eDP panels. > > > > Signed-off-by: Jouni Högander <jouni.hogander@intel.com> > > Fixes: 605f7c731333 ("drm/i915: Fix fast wake AUX sync len") > > Due to the cherry-picks I think it's better to reference e1c71f8f9180 > ("drm/i915: Fix fast wake AUX sync len") which has been backported to > stable. We need this fix to go wherever that's been backported. Ok, I will change this. > > What happens if we use cc: stable and this gets backported to a > kernel > that does *not* have "drm/i915: Fix fast wake AUX sync len"? Any harm > in > that? Our current understanding is that we should use 10 sync pulses for precharge. Which is actually the HW default. Original value our driver was writing before "drm/i915: Fix fast wake AUX sync len" was clearly wrong -> It should be right thing to do to backport this even if previous adjustment ("drm/i915: Fix fast wake AUX sync len") doesn't exist. BR, Jouni Högander > > BR, > Jani. > > > > > Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8475 > > --- > > drivers/gpu/drm/i915/display/intel_dp_aux.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c > > b/drivers/gpu/drm/i915/display/intel_dp_aux.c > > index 0c27db8ae4f1..197c6e81db14 100644 > > --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c > > +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c > > @@ -129,7 +129,7 @@ static int intel_dp_aux_sync_len(void) > > > > static int intel_dp_aux_fw_sync_len(void) > > { > > - int precharge = 16; /* 10-16 */ > > + int precharge = 10; /* 10-16 */ > > int preamble = 8; > > > > return precharge + preamble; >
diff --git a/drivers/gpu/drm/i915/display/intel_dp_aux.c b/drivers/gpu/drm/i915/display/intel_dp_aux.c index 0c27db8ae4f1..197c6e81db14 100644 --- a/drivers/gpu/drm/i915/display/intel_dp_aux.c +++ b/drivers/gpu/drm/i915/display/intel_dp_aux.c @@ -129,7 +129,7 @@ static int intel_dp_aux_sync_len(void) static int intel_dp_aux_fw_sync_len(void) { - int precharge = 16; /* 10-16 */ + int precharge = 10; /* 10-16 */ int preamble = 8; return precharge + preamble;
HW default for wake sync pulses is 18. 10 precarge and 8 preamble. There is no reason to change this especially as it is causing problems with certain eDP panels. Signed-off-by: Jouni Högander <jouni.hogander@intel.com> Fixes: 605f7c731333 ("drm/i915: Fix fast wake AUX sync len") Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/8475 --- drivers/gpu/drm/i915/display/intel_dp_aux.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)