<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:x="urn:schemas-microsoft-com:office:excel" xmlns:p="urn:schemas-microsoft-com:office:powerpoint" xmlns:a="urn:schemas-microsoft-com:office:access" xmlns:dt="uuid:C2F41010-65B3-11d1-A29F-00AA00C14882" xmlns:s="uuid:BDC6E3F0-6DA3-11d1-A2A3-00AA00C14882" xmlns:rs="urn:schemas-microsoft-com:rowset" xmlns:z="#RowsetSchema" xmlns:b="urn:schemas-microsoft-com:office:publisher" xmlns:ss="urn:schemas-microsoft-com:office:spreadsheet" xmlns:c="urn:schemas-microsoft-com:office:component:spreadsheet" xmlns:odc="urn:schemas-microsoft-com:office:odc" xmlns:oa="urn:schemas-microsoft-com:office:activation" xmlns:html="http://www.w3.org/TR/REC-html40" xmlns:q="http://schemas.xmlsoap.org/soap/envelope/" xmlns:rtc="http://microsoft.com/officenet/conferencing" xmlns:D="DAV:" xmlns:Repl="http://schemas.microsoft.com/repl/" xmlns:mt="http://schemas.microsoft.com/sharepoint/soap/meetings/" xmlns:x2="http://schemas.microsoft.com/office/excel/2003/xml" xmlns:ppda="http://www.passport.com/NameSpace.xsd" xmlns:ois="http://schemas.microsoft.com/sharepoint/soap/ois/" xmlns:dir="http://schemas.microsoft.com/sharepoint/soap/directory/" xmlns:ds="http://www.w3.org/2000/09/xmldsig#" xmlns:dsp="http://schemas.microsoft.com/sharepoint/dsp" xmlns:udc="http://schemas.microsoft.com/data/udc" xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:sub="http://schemas.microsoft.com/sharepoint/soap/2002/1/alerts/" xmlns:ec="http://www.w3.org/2001/04/xmlenc#" xmlns:sp="http://schemas.microsoft.com/sharepoint/" xmlns:sps="http://schemas.microsoft.com/sharepoint/soap/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:udcs="http://schemas.microsoft.com/data/udc/soap" xmlns:udcxf="http://schemas.microsoft.com/data/udc/xmlfile" xmlns:udcp2p="http://schemas.microsoft.com/data/udc/parttopart" xmlns:wf="http://schemas.microsoft.com/sharepoint/soap/workflow/" xmlns:dsss="http://schemas.microsoft.com/office/2006/digsig-setup" xmlns:dssi="http://schemas.microsoft.com/office/2006/digsig" xmlns:mdssi="http://schemas.openxmlformats.org/package/2006/digital-signature" xmlns:mver="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns:mrels="http://schemas.openxmlformats.org/package/2006/relationships" xmlns:spwp="http://microsoft.com/sharepoint/webpartpages" xmlns:ex12t="http://schemas.microsoft.com/exchange/services/2006/types" xmlns:ex12m="http://schemas.microsoft.com/exchange/services/2006/messages" xmlns:pptsl="http://schemas.microsoft.com/sharepoint/soap/SlideLibrary/" xmlns:spsl="http://microsoft.com/webservices/SharePointPortalServer/PublishedLinksService" xmlns:Z="urn:schemas-microsoft-com:" xmlns:tax="http://schemas.microsoft.com/sharepoint/taxonomy/soap/" xmlns:tns="http://schemas.microsoft.com/sharepoint/soap/recordsrepository/" xmlns:spsup="http://microsoft.com/webservices/SharePointPortalServer/UserProfileService" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:st="" xmlns="http://www.w3.org/TR/REC-html40"> <head> <meta http-equiv="Content-Type" content="text/html; charset=ks_c_5601-1987"> <meta name="Generator" content="Microsoft Word 14 (filtered medium)"> <style></style> </head> <body lang="ZH-TW" link="blue" vlink="purple" style="text-justify-trim:punctuation"> <div class="WordSection1"> Hi Jani Nikula<o:p></o:p> <o:p> </o:p> Thanks for your suggestion and I have replied two comments below.<o:p></o:p> <o:p> </o:p> -----Original Message----- From: Jani Nikula [mailto:jani.nikula@linux.intel.com] Sent: Wednesday, November 27, 2019 6:29 PM To: Allen Chen (��) Cc: Jau-Chih Tseng (��); Maxime Ripard; Allen Chen (��); open list; open list:DRM DRIVERS; David Airlie; Pi-Hsun Shih; Sean Paul Subject: Re: [PATCH] drm/edid: fixup EDID 1.3 and 1.4 judge reduced-blanking timings logic <o:p> </o:p> On Tue, 26 Nov 2019, allen <allen.chen@ite.com.tw> wrote:<o:p></o:p> > According to VESA ENHANCED EXTENDED DISPLAY IDENTIFICATION DATA STANDARD<o:p></o:p> > (Defines EDID Structure Version 1, Revision 4) page: 39<o:p></o:p> > How to determine whether the monitor support RB timing or not?<o:p></o:p> > EDID 1.4<o:p></o:p> > First: read detailed timing descriptor and make sure byte 0 = 0x00,<o:p></o:p> > byte 1 = 0x00, byte 2 = 0x00 and byte 3 = 0xFD<o:p></o:p> > Second: read EDID bit 0 in feature support byte at address 18h = 1<o:p></o:p> > and detailed timing descriptor byte 10 = 0x04<o:p></o:p> > Third: if EDID bit 0 in feature support byte = 1 &&<o:p></o:p> > detailed timing descriptor byte 10 = 0x04<o:p></o:p> > then we can check byte 15, if bit 4 in byte 15 = 1 is support RB<o:p></o:p> > if EDID bit 0 in feature support byte != 1 ||<o:p></o:p> > detailed timing descriptor byte 10 != 0x04,<o:p></o:p> > then byte 15 can not be used<o:p></o:p> ><o:p> </o:p> > The linux code is_rb function not follow the VESA's rule<o:p></o:p> ><o:p> </o:p> > Signed-off-by: Allen Chen <allen.chen@ite.com.tw><o:p></o:p> > Reported-by: kbuild test robot <lkp@intel.com><o:p></o:p> > ---<o:p></o:p> > drivers/gpu/drm/drm_edid.c | 36 ++++++++++++++++++++++++++++++------<o:p></o:p> > 1 file changed, 30 insertions(+), 6 deletions(-)<o:p></o:p> ><o:p> </o:p> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c<o:p></o:p> > index f5926bf..e11e585 100644<o:p></o:p> > --- a/drivers/gpu/drm/drm_edid.c<o:p></o:p> > +++ b/drivers/gpu/drm/drm_edid.c<o:p></o:p> > @@ -93,6 +93,12 @@ struct detailed_mode_closure {<o:p></o:p> > int modes;<o:p></o:p> > };<o:p></o:p> > <o:p></o:p> > +struct edid_support_rb_closure {<o:p></o:p> > + struct edid *edid;<o:p></o:p> > + bool valid_support_rb;<o:p></o:p> > + bool support_rb;<o:p></o:p> > +};<o:p></o:p> > +<o:p></o:p> > #define LEVEL_DMT 0<o:p></o:p> > #define LEVEL_GTF 1<o:p></o:p> > #define LEVEL_GTF2 2<o:p></o:p> > @@ -2017,23 +2023,41 @@ struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,<o:p></o:p> > }<o:p></o:p> > }<o:p></o:p> > <o:p></o:p> > +static bool<o:p></o:p> > +is_display_descriptor(const u8 *r, u8 tag)<o:p></o:p> > +{<o:p></o:p> > + return (!r[0] && !r[1] && !r[2] && r[3] == tag) ? true : false;<o:p></o:p> > +}<o:p></o:p> > +<o:p></o:p> > static void<o:p></o:p> > is_rb(struct detailed_timing *t, void *data)<o:p></o:p> > {<o:p></o:p> > u8 *r = (u8 *)t;<o:p></o:p> > - if (r[3] == EDID_DETAIL_MONITOR_RANGE)<o:p></o:p> > - if (r[15] & 0x10)<o:p></o:p> > - *(bool *)data = true;<o:p></o:p> > + struct edid_support_rb_closure *closure = data;<o:p></o:p> > + struct edid *edid = closure->edid;<o:p></o:p> > +<o:p></o:p> > + if (is_display_descriptor(r, EDID_DETAIL_MONITOR_RANGE)) {<o:p></o:p> > + if (edid->features & BIT(0) && r[10] == BIT(2)) {<o:p></o:p> > + closure->valid_support_rb = true;<o:p></o:p> > + closure->support_rb = (r[15] & 0x10) ? true : false;<o:p></o:p> > + }<o:p></o:p> > + }<o:p></o:p> > }<o:p></o:p> > <o:p></o:p> > /* EDID 1.4 defines this explicitly. For EDID 1.3, we guess, badly. */<o:p></o:p> > static bool<o:p></o:p> > drm_monitor_supports_rb(struct edid *edid)<o:p></o:p> > {<o:p></o:p> > + struct edid_support_rb_closure closure = {<o:p></o:p> > + .edid = edid,<o:p></o:p> > + .valid_support_rb = false,<o:p></o:p> > + .support_rb = false,<o:p></o:p> > + };<o:p></o:p> > +<o:p></o:p> > if (edid->revision >= 4) {<o:p></o:p> > - bool ret = false;<o:p></o:p> > - drm_for_each_detailed_block((u8 *)edid, is_rb, &ret);<o:p></o:p> > - return ret;<o:p></o:p> > + drm_for_each_detailed_block((u8 *)edid, is_rb, &closure);<o:p></o:p> > + if (closure.valid_support_rb)<o:p></o:p> > + return closure.support_rb;<o:p></o:p> <o:p> </o:p> Are you planning on extending the closure use somehow?<o:p></o:p> <o:p> </o:p> I did not look up the spec, <o:p></o:p> <o:p> </o:p> ==> iTE: as the picture below, from VESA E-EDID standard<o:p></o:p> <img width="383" height="214" id="��_x0020_1" src="cid:image003.jpg@01D5A9EA.9B7364D0"> <o:p></o:p> <o:p> </o:p> <img width="476" height="77" id="��_x0020_4" src="cid:image005.jpg@01D5A9EA.9B7364D0"><o:p></o:p> <o:p> </o:p> if EDID bit 0 in feature support byte = 1 && detailed timing descriptor byte 10 = 0x04 then the CVT timing supported.<o:p></o:p> <o:p> </o:p> <img width="480" height="104" id="��_x0020_3" src="cid:image009.jpg@01D5A9EA.9B7364D0"><o:p></o:p> <o:p> </o:p> If CVT timing supported then we can check byte 15 bit 4 to determine whether the reduced-blanking timings suported or not.<o:p></o:p> If CVT timing not supported then we can not use byte 15 to judge.<o:p></o:p> but purely on the code changes alone, you<o:p></o:p> could just move the edid->features bit check at this level, and not pass<o:p></o:p> it down, and nothing would change. I.e. don't iterate the EDID at all if<o:p></o:p> the bit is not set.<o:p></o:p> <o:p> </o:p> <![if !supportLists]>�� <![endif]>iTE: We still have to check whether detailed timing descriptor byte 10 = 0x04 or not, so it is hard to check at this level<o:p></o:p> You also don't actually use the distinction between valid_support_rb<o:p></o:p> vs. support_rb for anything, so the closure just adds code.<o:p></o:p> <o:p> </o:p> BR,<o:p></o:p> Jani.<o:p></o:p> <o:p> </o:p> <o:p> </o:p> > }<o:p></o:p> > <o:p></o:p> > return ((edid->input & DRM_EDID_INPUT_DIGITAL) != 0);<o:p></o:p> <o:p> </o:p> -- <o:p></o:p> Jani Nikula, Intel Open Source Graphics Center<o:p></o:p> </div> </body> </html>