Skip to content

Commit

Permalink
drm/edid: Add secondary GTF curve support
Browse files Browse the repository at this point in the history 
Before CVT-R, some monitors would advertise support for an alternative
GTF formula with lower blanking intervals.  Correctly identify such
monitors, and use the alternative formula when generating modes for
them.

Note that we only do this for "standard" timing descriptors (tuples of
hsize in characters / aspect ratio / vertical refresh).  Range-based
mode lists still only refer to the primary GTF curve.  It would be
possible to do better for the latter case, but monitors are required to
support the primary curve over the entire advertised range, so all it
would win you is a lower pixel clock and therefore possibly better image
quality on analog links.

Signed-off-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
  • Loading branch information
Adam Jackson authored and Dave Airlie committed Apr 6, 2010
1 parent 7ca6adb commit 7a37435
Show file tree
Hide file tree
Showing 3 changed files with 150 additions and 54 deletions.
119 changes: 92 additions & 27 deletions drivers/gpu/drm/drm_edid.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -64,7 +64,8 @@

#define LEVEL_DMT 0
#define LEVEL_GTF 1
#define LEVEL_CVT 2
#define LEVEL_GTF2 2
#define LEVEL_CVT 3

static struct edid_quirk {
char *vendor;
Expand Down Expand Up @@ -713,6 +714,71 @@ drm_monitor_supports_rb(struct edid *edid)
return ((edid->input & DRM_EDID_INPUT_DIGITAL) != 0);
}

static void
find_gtf2(struct detailed_timing *t, void *data)
{
u8 *r = (u8 *)t;
if (r[3] == EDID_DETAIL_MONITOR_RANGE && r[10] == 0x02)
*(u8 **)data = r;
}

/* Secondary GTF curve kicks in above some break frequency */
static int
drm_gtf2_hbreak(struct edid *edid)
{
u8 *r = NULL;
drm_for_each_detailed_block((u8 *)edid, find_gtf2, &r);
return r ? (r[12] * 2) : 0;
}

static int
drm_gtf2_2c(struct edid *edid)
{
u8 *r = NULL;
drm_for_each_detailed_block((u8 *)edid, find_gtf2, &r);
return r ? r[13] : 0;
}

static int
drm_gtf2_m(struct edid *edid)
{
u8 *r = NULL;
drm_for_each_detailed_block((u8 *)edid, find_gtf2, &r);
return r ? (r[15] << 8) + r[14] : 0;
}

static int
drm_gtf2_k(struct edid *edid)
{
u8 *r = NULL;
drm_for_each_detailed_block((u8 *)edid, find_gtf2, &r);
return r ? r[16] : 0;
}

static int
drm_gtf2_2j(struct edid *edid)
{
u8 *r = NULL;
drm_for_each_detailed_block((u8 *)edid, find_gtf2, &r);
return r ? r[17] : 0;
}

/**
* standard_timing_level - get std. timing level(CVT/GTF/DMT)
* @edid: EDID block to scan
*/
static int standard_timing_level(struct edid *edid)
{
if (edid->revision >= 2) {
if (edid->revision >= 4 && (edid->features & DRM_EDID_FEATURE_DEFAULT_GTF))
return LEVEL_CVT;
if (drm_gtf2_hbreak(edid))
return LEVEL_GTF2;
return LEVEL_GTF;
}
return LEVEL_DMT;
}

/*
* 0 is reserved. The spec says 0x01 fill for unused timings. Some old
* monitors fill with ascii space (0x20) instead.
Expand All @@ -734,8 +800,8 @@ bad_std_timing(u8 a, u8 b)
* and convert them into a real mode using CVT/GTF/DMT.
*/
static struct drm_display_mode *
drm_mode_std(struct drm_connector *connector, struct std_timing *t,
int revision, int timing_level)
drm_mode_std(struct drm_connector *connector, struct edid *edid,
struct std_timing *t, int revision)
{
struct drm_device *dev = connector->dev;
struct drm_display_mode *m, *mode = NULL;
Expand All @@ -745,6 +811,7 @@ drm_mode_std(struct drm_connector *connector, struct std_timing *t,
>> EDID_TIMING_ASPECT_SHIFT;
unsigned vfreq = (t->vfreq_aspect & EDID_TIMING_VFREQ_MASK)
>> EDID_TIMING_VFREQ_SHIFT;
int timing_level = standard_timing_level(edid);

if (bad_std_timing(t->hsize, t->vfreq_aspect))
return NULL;
Expand Down Expand Up @@ -806,6 +873,23 @@ drm_mode_std(struct drm_connector *connector, struct std_timing *t,
case LEVEL_GTF:
mode = drm_gtf_mode(dev, hsize, vsize, vrefresh_rate, 0, 0);
break;
case LEVEL_GTF2:
/*
* This is potentially wrong if there's ever a monitor with
* more than one ranges section, each claiming a different
* secondary GTF curve. Please don't do that.
*/
mode = drm_gtf_mode(dev, hsize, vsize, vrefresh_rate, 0, 0);
if (drm_mode_hsync(mode) > drm_gtf2_hbreak(edid)) {
kfree(mode);
mode = drm_gtf_mode_complex(dev, hsize, vsize,
vrefresh_rate, 0, 0,
drm_gtf2_m(edid),
drm_gtf2_2c(edid),
drm_gtf2_k(edid),
drm_gtf2_2j(edid));
}
break;
case LEVEL_CVT:
mode = drm_cvt_mode(dev, hsize, vsize, vrefresh_rate, 0, 0,
false);
Expand Down Expand Up @@ -1042,19 +1126,6 @@ static int add_established_modes(struct drm_connector *connector, struct edid *e

return modes;
}
/**
* stanard_timing_level - get std. timing level(CVT/GTF/DMT)
* @edid: EDID block to scan
*/
static int standard_timing_level(struct edid *edid)
{
if (edid->revision >= 2) {
if (edid->revision >= 4 && (edid->features & DRM_EDID_FEATURE_DEFAULT_GTF))
return LEVEL_CVT;
return LEVEL_GTF;
}
return LEVEL_DMT;
}

/**
* add_standard_modes - get std. modes from EDID and add them
Expand All @@ -1066,15 +1137,13 @@ static int standard_timing_level(struct edid *edid)
static int add_standard_modes(struct drm_connector *connector, struct edid *edid)
{
int i, modes = 0;
int timing_level;

timing_level = standard_timing_level(edid);

for (i = 0; i < EDID_STD_TIMINGS; i++) {
struct drm_display_mode *newmode;

newmode = drm_mode_std(connector, &edid->standard_timings[i],
edid->revision, timing_level);
newmode = drm_mode_std(connector, edid,
&edid->standard_timings[i],
edid->revision);
if (newmode) {
drm_mode_probed_add(connector, newmode);
modes++;
Expand Down Expand Up @@ -1140,9 +1209,6 @@ range_pixel_clock(struct edid *edid, u8 *t)
return t[9] * 10000 + 5001;
}

/*
* XXX fix this for GTF secondary curve formula
*/
static bool
mode_in_range(struct drm_display_mode *mode, struct edid *edid,
struct detailed_timing *timing)
Expand Down Expand Up @@ -1339,7 +1405,6 @@ static int add_detailed_modes(struct drm_connector *connector,
{
int i, modes = 0;
struct detailed_non_pixel *data = &timing->data.other_data;
int timing_level = standard_timing_level(edid);
int gtf = (edid->features & DRM_EDID_FEATURE_DEFAULT_GTF);
struct drm_display_mode *newmode;
struct drm_device *dev = connector->dev;
Expand Down Expand Up @@ -1370,8 +1435,8 @@ static int add_detailed_modes(struct drm_connector *connector,
struct drm_display_mode *newmode;

std = &data->data.timings[i];
newmode = drm_mode_std(connector, std, edid->revision,
timing_level);
newmode = drm_mode_std(connector, edid, std,
edid->revision);
if (newmode) {
drm_mode_probed_add(connector, newmode);
modes++;
Expand Down
81 changes: 54 additions & 27 deletions drivers/gpu/drm/drm_modes.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -276,35 +276,29 @@ struct drm_display_mode *drm_cvt_mode(struct drm_device *dev, int hdisplay,
EXPORT_SYMBOL(drm_cvt_mode);

/**
* drm_gtf_mode - create the modeline based on GTF algorithm
* drm_gtf_mode_complex - create the modeline based on full GTF algorithm
*
* @dev :drm device
* @hdisplay :hdisplay size
* @vdisplay :vdisplay size
* @vrefresh :vrefresh rate.
* @interlaced :whether the interlace is supported
* @margins :whether the margin is supported
* @margins :desired margin size
* @GTF_[MCKJ] :extended GTF formula parameters
*
* LOCKING.
* none.
*
* return the modeline based on GTF algorithm
*
* This function is to create the modeline based on the GTF algorithm.
* Generalized Timing Formula is derived from:
* GTF Spreadsheet by Andy Morrish (1/5/97)
* available at http://www.vesa.org
* return the modeline based on full GTF algorithm.
*
* And it is copied from the file of xserver/hw/xfree86/modes/xf86gtf.c.
* What I have done is to translate it by using integer calculation.
* I also refer to the function of fb_get_mode in the file of
* drivers/video/fbmon.c
* GTF feature blocks specify C and J in multiples of 0.5, so we pass them
* in here multiplied by two. For a C of 40, pass in 80.
*/
struct drm_display_mode *drm_gtf_mode(struct drm_device *dev, int hdisplay,
int vdisplay, int vrefresh,
bool interlaced, int margins)
{
/* 1) top/bottom margin size (% of height) - default: 1.8, */
struct drm_display_mode *
drm_gtf_mode_complex(struct drm_device *dev, int hdisplay, int vdisplay,
int vrefresh, bool interlaced, int margins,
int GTF_M, int GTF_2C, int GTF_K, int GTF_2J)
{ /* 1) top/bottom margin size (% of height) - default: 1.8, */
#define GTF_MARGIN_PERCENTAGE 18
/* 2) character cell horizontal granularity (pixels) - default 8 */
#define GTF_CELL_GRAN 8
Expand All @@ -316,17 +310,9 @@ struct drm_display_mode *drm_gtf_mode(struct drm_device *dev, int hdisplay,
#define H_SYNC_PERCENT 8
/* min time of vsync + back porch (microsec) */
#define MIN_VSYNC_PLUS_BP 550
/* blanking formula gradient */
#define GTF_M 600
/* blanking formula offset */
#define GTF_C 40
/* blanking formula scaling factor */
#define GTF_K 128
/* blanking formula scaling factor */
#define GTF_J 20
/* C' and M' are part of the Blanking Duty Cycle computation */
#define GTF_C_PRIME (((GTF_C - GTF_J) * GTF_K / 256) + GTF_J)
#define GTF_M_PRIME (GTF_K * GTF_M / 256)
#define GTF_C_PRIME ((((GTF_2C - GTF_2J) * GTF_K / 256) + GTF_2J) / 2)
#define GTF_M_PRIME (GTF_K * GTF_M / 256)
struct drm_display_mode *drm_mode;
unsigned int hdisplay_rnd, vdisplay_rnd, vfieldrate_rqd;
int top_margin, bottom_margin;
Expand Down Expand Up @@ -470,7 +456,48 @@ struct drm_display_mode *drm_gtf_mode(struct drm_device *dev, int hdisplay,

return drm_mode;
}
EXPORT_SYMBOL(drm_gtf_mode_complex);

/**
* drm_gtf_mode - create the modeline based on GTF algorithm
*
* @dev :drm device
* @hdisplay :hdisplay size
* @vdisplay :vdisplay size
* @vrefresh :vrefresh rate.
* @interlaced :whether the interlace is supported
* @margins :whether the margin is supported
*
* LOCKING.
* none.
*
* return the modeline based on GTF algorithm
*
* This function is to create the modeline based on the GTF algorithm.
* Generalized Timing Formula is derived from:
* GTF Spreadsheet by Andy Morrish (1/5/97)
* available at http://www.vesa.org
*
* And it is copied from the file of xserver/hw/xfree86/modes/xf86gtf.c.
* What I have done is to translate it by using integer calculation.
* I also refer to the function of fb_get_mode in the file of
* drivers/video/fbmon.c
*
* Standard GTF parameters:
* M = 600
* C = 40
* K = 128
* J = 20
*/
struct drm_display_mode *
drm_gtf_mode(struct drm_device *dev, int hdisplay, int vdisplay, int vrefresh,
bool lace, int margins)
{
return drm_gtf_mode_complex(dev, hdisplay, vdisplay, vrefresh, lace,
margins, 600, 40 * 2, 128, 20 * 2);
}
EXPORT_SYMBOL(drm_gtf_mode);

/**
* drm_mode_set_name - set the name on a mode
* @mode: name will be set in this mode
Expand Down
4 changes: 4 additions & 0 deletions include/drm/drm_crtc.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -797,6 +797,10 @@ extern struct drm_display_mode *drm_cvt_mode(struct drm_device *dev,
extern struct drm_display_mode *drm_gtf_mode(struct drm_device *dev,
int hdisplay, int vdisplay, int vrefresh,
bool interlaced, int margins);
extern struct drm_display_mode *drm_gtf_mode_complex(struct drm_device *dev,
int hdisplay, int vdisplay, int vrefresh,
bool interlaced, int margins, int GTF_M,
int GTF_2C, int GTF_K, int GTF_2J);
extern int drm_add_modes_noedid(struct drm_connector *connector,
int hdisplay, int vdisplay);

Expand Down

0 comments on commit 7a37435

Please sign in to comment.