fbdev: sh_mobile_hdmi: add command line option to use the preferred EDID mode

Currently, if no command-line option is specified, the sh_mobile_hdmi
will use the default 720p video mode. If a command line option of the
form "video=sh_mobile_lcdc:<width>x<height>@<refresh>" is provided,
the driver will look for that mode among those, available in the
monitor EDID. This patch adds the ability to request the driver to
use monitor's preferred mode by specifying 0 as width and hight in
the above string. If that mode is not supported by the system, the
driver will continue scanning through EDID modes, until it finds a
suitable one.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

diff --git a/drivers/video/sh_mobile_hdmi.c b/drivers/video/sh_mobile_hdmi.c
index 8c59cc8c5a9c2c728b2f76e7fe4cb9679cad9bd9..571bd9f74513cc8506edbd31b77aed70a1c0e9ba 100644 (file)
--- a/drivers/video/sh_mobile_hdmi.c
+++ b/drivers/video/sh_mobile_hdmi.c
@@ -737,7 +737,7 @@ static int sh_hdmi_read_edid(struct sh_hdmi *hdmi, unsigned long *hdmi_rate,
        struct fb_modelist *modelist = NULL;
        unsigned int f_width = 0, f_height = 0, f_refresh = 0;
        unsigned long found_rate_error = ULONG_MAX; /* silly compiler... */
-       bool exact_match = false;
+       bool scanning = false, preferred_bad = false;
        u8 edid[128];
        char *forced;
        int i;
@@ -800,6 +800,9 @@ static int sh_hdmi_read_edid(struct sh_hdmi *hdmi, unsigned long *hdmi_rate,
                if (i < 2) {
                        f_width = 0;
                        f_height = 0;
+               } else {
+                       /* The user wants us to use the EDID data */
+                       scanning = true;
                }
                dev_dbg(hdmi->dev, "Forced mode %ux%u@%uHz\n",
                        f_width, f_height, f_refresh);
@@ -807,37 +810,56 @@ static int sh_hdmi_read_edid(struct sh_hdmi *hdmi, unsigned long *hdmi_rate,
 
        /* Walk monitor modes to find the best or the exact match */
        for (i = 0, mode = hdmi->monspec.modedb;
-            f_width && f_height && i < hdmi->monspec.modedb_len && !exact_match;
+            i < hdmi->monspec.modedb_len && scanning;
             i++, mode++) {
                unsigned long rate_error;
 
-               /* No interest in unmatching modes */
-               if (f_width != mode->xres || f_height != mode->yres)
+               if (!f_width && !f_height) {
+                       /*
+                        * A parameter string "video=sh_mobile_lcdc:0x0" means
+                        * use the preferred EDID mode. If it is rejected by
+                        * .fb_check_var(), keep looking, until an acceptable
+                        * one is found.
+                        */
+                       if ((mode->flag & FB_MODE_IS_FIRST) || preferred_bad)
+                               scanning = false;
+                       else
+                               continue;
+               } else if (f_width != mode->xres || f_height != mode->yres) {
+                       /* No interest in unmatching modes */
                        continue;
+               }
 
                rate_error = sh_hdmi_rate_error(hdmi, mode, hdmi_rate, parent_rate);
 
-               if (f_refresh == mode->refresh || (!f_refresh && !rate_error))
-                       /*
-                        * Exact match if either the refresh rate matches or it
-                        * hasn't been specified and we've found a mode, for
-                        * which we can configure the clock precisely
-                        */
-                       exact_match = true;
-               else if (found && found_rate_error <= rate_error)
-                       /*
-                        * We otherwise search for the closest matching clock
-                        * rate - either if no refresh rate has been specified
-                        * or we cannot find an exactly matching one
-                        */
-                       continue;
+               if (scanning) {
+                       if (f_refresh == mode->refresh || (!f_refresh && !rate_error))
+                               /*
+                                * Exact match if either the refresh rate
+                                * matches or it hasn't been specified and we've
+                                * found a mode, for which we can configure the
+                                * clock precisely
+                                */
+                               scanning = false;
+                       else if (found && found_rate_error <= rate_error)
+                               /*
+                                * We otherwise search for the closest matching
+                                * clock rate - either if no refresh rate has
+                                * been specified or we cannot find an exactly
+                                * matching one
+                                */
+                               continue;
+               }
 
                /* Check if supported: sufficient fb memory, supported clock-rate */
                fb_videomode_to_var(var, mode);
 
+               var->bits_per_pixel = info->var.bits_per_pixel;
+
                if (info && info->fbops->fb_check_var &&
                    info->fbops->fb_check_var(var, info)) {
-                       exact_match = false;
+                       scanning = true;
+                       preferred_bad = true;
                        continue;
                }