From: "Lin, Wayne" <Wayne.Lin@amd.com> To: "Ville Syrjälä" <ville.syrjala@linux.intel.com> Cc: "Brol, Eryk" <Eryk.Brol@amd.com>, "Zhuo, Qingqing" <Qingqing.Zhuo@amd.com>, "stable@vger.kernel.org" <stable@vger.kernel.org>, "Zuo, Jerry" <Jerry.Zuo@amd.com>, "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>, "Kazlauskas, Nicholas" <Nicholas.Kazlauskas@amd.com> Subject: RE: [PATCH 1/2] drm/dp_mst: Revise broadcast msg lct & lcr Date: Wed, 24 Feb 2021 09:47:42 +0000 [thread overview] Message-ID: <BN8PR12MB4770DDD0992FDBFEA2E573FCFC9F9@BN8PR12MB4770.namprd12.prod.outlook.com> (raw) In-Reply-To: <YDUChEqKeqw1znMc@intel.com> [AMD Public Use] > -----Original Message----- > From: Ville Syrjälä <ville.syrjala@linux.intel.com> > Sent: Tuesday, February 23, 2021 9:26 PM > To: Lin, Wayne <Wayne.Lin@amd.com> > Cc: Brol, Eryk <Eryk.Brol@amd.com>; Zhuo, Qingqing <Qingqing.Zhuo@amd.com>; stable@vger.kernel.org; Zuo, Jerry > <Jerry.Zuo@amd.com>; dri-devel@lists.freedesktop.org; Kazlauskas, Nicholas <Nicholas.Kazlauskas@amd.com> > Subject: Re: [PATCH 1/2] drm/dp_mst: Revise broadcast msg lct & lcr > > On Tue, Feb 23, 2021 at 05:32:32AM +0000, Lin, Wayne wrote: > > [AMD Public Use] > > > > > -----Original Message----- > > > From: Ville Syrjälä <ville.syrjala@linux.intel.com> > > > Sent: Tuesday, February 23, 2021 1:09 AM > > > To: Lin, Wayne <Wayne.Lin@amd.com> > > > Cc: Brol, Eryk <Eryk.Brol@amd.com>; Zhuo, Qingqing > > > <Qingqing.Zhuo@amd.com>; stable@vger.kernel.org; Zuo, Jerry > > > <Jerry.Zuo@amd.com>; dri-devel@lists.freedesktop.org; Kazlauskas, > > > Nicholas <Nicholas.Kazlauskas@amd.com> > > > Subject: Re: [PATCH 1/2] drm/dp_mst: Revise broadcast msg lct & lcr > > > > > > On Mon, Feb 22, 2021 at 07:02:03PM +0200, Ville Syrjälä wrote: > > > > On Mon, Feb 22, 2021 at 12:00:26PM +0800, Wayne Lin wrote: > > > > > [Why & How] > > > > > According to DP spec, broadcast message LCT equals to 1 and LCR > > > > > equals to 6. Current implementation is incorrect. Fix it. > > > > > > > > > > Signed-off-by: Wayne Lin <Wayne.Lin@amd.com> > > > > > Cc: stable@vger.kernel.org > > > > > --- > > > > > drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++++-- > > > > > 1 file changed, 8 insertions(+), 2 deletions(-) > > > > > > > > > > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c > > > > > b/drivers/gpu/drm/drm_dp_mst_topology.c > > > > > index 17dbed0a9800..713ef3b42054 100644 > > > > > --- a/drivers/gpu/drm/drm_dp_mst_topology.c > > > > > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c > > > > > @@ -2727,8 +2727,14 @@ static int set_hdr_from_dst_qlock(struct > > > > > drm_dp_sideband_msg_hdr *hdr, else hdr->broadcast = 0; > > > > > hdr->path_msg = txmsg->path_msg; > > > > > -hdr->lct = mstb->lct; > > > > > -hdr->lcr = mstb->lct - 1; > > > > > +if (hdr->broadcast) { > > > > > +hdr->lct = 1; > > > > > +hdr->lcr = 6; > > > > > +} else { > > > > > +hdr->lct = mstb->lct; > > > > > +hdr->lcr = mstb->lct - 1; > > > > > +} > > > > > + > > > > > if (mstb->lct > 1) > > > > > memcpy(hdr->rad, mstb->rad, mstb->lct / 2); > > > > > > > > We should also do something about RAD no? > > > > > > Just skip the RAD stuff by s/mstb->lct/hdr->lct/ here I guess? > > Thanks Ville! > > Since LCT=1, broadcast message doesn't have a RAD and this is taken > > care while we're constructing the header in drm_dp_encode_sideband_msg_hdr(). > > In drm_dp_encode_sideband_msg_hdr(), we skip stuffing RAD if LCT=1. > > Ugh. How many levels of these do we really need... > Either way I'd prefer the code be consistent so you don't have to sacrifice so many brain cells to understand what should be trivial > details. Hi Ville, Ya I know.. Currently it goes few levels to encapsulate the final mst packet. From my understanding, this function is trying to prepare needed data and the actual mst packet header is constructed in drm_dp_encode_sideband_msg_hdr(). However, I will push another version by your suggestion. Thanks for your time! > > -- > Ville Syrjälä > Intel Regards, Wayne Lin
WARNING: multiple messages have this Message-ID (diff)
From: "Lin, Wayne" <Wayne.Lin@amd.com> To: "Ville Syrjälä" <ville.syrjala@linux.intel.com> Cc: "Brol, Eryk" <Eryk.Brol@amd.com>, "Zhuo, Qingqing" <Qingqing.Zhuo@amd.com>, "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>, "Zuo, Jerry" <Jerry.Zuo@amd.com>, "stable@vger.kernel.org" <stable@vger.kernel.org>, "Kazlauskas, Nicholas" <Nicholas.Kazlauskas@amd.com> Subject: RE: [PATCH 1/2] drm/dp_mst: Revise broadcast msg lct & lcr Date: Wed, 24 Feb 2021 09:47:42 +0000 [thread overview] Message-ID: <BN8PR12MB4770DDD0992FDBFEA2E573FCFC9F9@BN8PR12MB4770.namprd12.prod.outlook.com> (raw) In-Reply-To: <YDUChEqKeqw1znMc@intel.com> [AMD Public Use] > -----Original Message----- > From: Ville Syrjälä <ville.syrjala@linux.intel.com> > Sent: Tuesday, February 23, 2021 9:26 PM > To: Lin, Wayne <Wayne.Lin@amd.com> > Cc: Brol, Eryk <Eryk.Brol@amd.com>; Zhuo, Qingqing <Qingqing.Zhuo@amd.com>; stable@vger.kernel.org; Zuo, Jerry > <Jerry.Zuo@amd.com>; dri-devel@lists.freedesktop.org; Kazlauskas, Nicholas <Nicholas.Kazlauskas@amd.com> > Subject: Re: [PATCH 1/2] drm/dp_mst: Revise broadcast msg lct & lcr > > On Tue, Feb 23, 2021 at 05:32:32AM +0000, Lin, Wayne wrote: > > [AMD Public Use] > > > > > -----Original Message----- > > > From: Ville Syrjälä <ville.syrjala@linux.intel.com> > > > Sent: Tuesday, February 23, 2021 1:09 AM > > > To: Lin, Wayne <Wayne.Lin@amd.com> > > > Cc: Brol, Eryk <Eryk.Brol@amd.com>; Zhuo, Qingqing > > > <Qingqing.Zhuo@amd.com>; stable@vger.kernel.org; Zuo, Jerry > > > <Jerry.Zuo@amd.com>; dri-devel@lists.freedesktop.org; Kazlauskas, > > > Nicholas <Nicholas.Kazlauskas@amd.com> > > > Subject: Re: [PATCH 1/2] drm/dp_mst: Revise broadcast msg lct & lcr > > > > > > On Mon, Feb 22, 2021 at 07:02:03PM +0200, Ville Syrjälä wrote: > > > > On Mon, Feb 22, 2021 at 12:00:26PM +0800, Wayne Lin wrote: > > > > > [Why & How] > > > > > According to DP spec, broadcast message LCT equals to 1 and LCR > > > > > equals to 6. Current implementation is incorrect. Fix it. > > > > > > > > > > Signed-off-by: Wayne Lin <Wayne.Lin@amd.com> > > > > > Cc: stable@vger.kernel.org > > > > > --- > > > > > drivers/gpu/drm/drm_dp_mst_topology.c | 10 ++++++++-- > > > > > 1 file changed, 8 insertions(+), 2 deletions(-) > > > > > > > > > > diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c > > > > > b/drivers/gpu/drm/drm_dp_mst_topology.c > > > > > index 17dbed0a9800..713ef3b42054 100644 > > > > > --- a/drivers/gpu/drm/drm_dp_mst_topology.c > > > > > +++ b/drivers/gpu/drm/drm_dp_mst_topology.c > > > > > @@ -2727,8 +2727,14 @@ static int set_hdr_from_dst_qlock(struct > > > > > drm_dp_sideband_msg_hdr *hdr, else hdr->broadcast = 0; > > > > > hdr->path_msg = txmsg->path_msg; > > > > > -hdr->lct = mstb->lct; > > > > > -hdr->lcr = mstb->lct - 1; > > > > > +if (hdr->broadcast) { > > > > > +hdr->lct = 1; > > > > > +hdr->lcr = 6; > > > > > +} else { > > > > > +hdr->lct = mstb->lct; > > > > > +hdr->lcr = mstb->lct - 1; > > > > > +} > > > > > + > > > > > if (mstb->lct > 1) > > > > > memcpy(hdr->rad, mstb->rad, mstb->lct / 2); > > > > > > > > We should also do something about RAD no? > > > > > > Just skip the RAD stuff by s/mstb->lct/hdr->lct/ here I guess? > > Thanks Ville! > > Since LCT=1, broadcast message doesn't have a RAD and this is taken > > care while we're constructing the header in drm_dp_encode_sideband_msg_hdr(). > > In drm_dp_encode_sideband_msg_hdr(), we skip stuffing RAD if LCT=1. > > Ugh. How many levels of these do we really need... > Either way I'd prefer the code be consistent so you don't have to sacrifice so many brain cells to understand what should be trivial > details. Hi Ville, Ya I know.. Currently it goes few levels to encapsulate the final mst packet. From my understanding, this function is trying to prepare needed data and the actual mst packet header is constructed in drm_dp_encode_sideband_msg_hdr(). However, I will push another version by your suggestion. Thanks for your time! > > -- > Ville Syrjälä > Intel Regards, Wayne Lin _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2021-02-24 9:50 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-02-22 4:00 [PATCH 0/2] Set CLEAR_PAYLOAD_ID_TABLE as broadcast request Wayne Lin 2021-02-22 4:00 ` Wayne Lin 2021-02-22 4:00 ` [PATCH 1/2] drm/dp_mst: Revise broadcast msg lct & lcr Wayne Lin 2021-02-22 4:00 ` Wayne Lin 2021-02-22 17:02 ` Ville Syrjälä 2021-02-22 17:02 ` Ville Syrjälä 2021-02-22 17:09 ` Ville Syrjälä 2021-02-22 17:09 ` Ville Syrjälä 2021-02-23 5:32 ` Lin, Wayne 2021-02-23 5:32 ` Lin, Wayne 2021-02-23 13:26 ` Ville Syrjälä 2021-02-23 13:26 ` Ville Syrjälä 2021-02-24 9:47 ` Lin, Wayne [this message] 2021-02-24 9:47 ` Lin, Wayne 2021-02-22 4:00 ` [PATCH 2/2] drm/dp_mst: Set CLEAR_PAYLOAD_ID_TABLE as broadcast Wayne Lin 2021-02-22 4:00 ` Wayne Lin 2021-02-22 17:00 ` Ville Syrjälä 2021-02-22 17:00 ` Ville Syrjälä 2021-02-23 5:32 ` Lin, Wayne 2021-02-23 5:32 ` Lin, Wayne 2021-02-23 13:21 ` Ville Syrjälä 2021-02-23 13:21 ` Ville Syrjälä 2021-02-24 18:06 ` [PATCH 0/2] Set CLEAR_PAYLOAD_ID_TABLE as broadcast request Lyude Paul 2021-02-24 18:06 ` Lyude Paul
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