fbdev: sh_mobile_hdmi: add support for more precise HDMI clock configuration

The HDMI clock has to be reconfigured for different video modes. However, the
precision of the supplying SoC clock on SH-Mobile systems is often
insufficient. This patch allows to additionally reconfigure the parent clock
to achieve the optimal HDMI clock frequency, in case this is supported by the
platform.

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 d7df103..ef41c21 100644 (file)
--- a/drivers/video/sh_mobile_hdmi.c
+++ b/drivers/video/sh_mobile_hdmi.c
@@ -685,11 +685,21 @@ static void sh_hdmi_configure(struct sh_hdmi *hdmi)
 }
 
 static unsigned long sh_hdmi_rate_error(struct sh_hdmi *hdmi,
-                                       const struct fb_videomode *mode)
+               const struct fb_videomode *mode,
+               unsigned long *hdmi_rate, unsigned long *parent_rate)
 {
-       long target = PICOS2KHZ(mode->pixclock) * 1000,
-               rate = clk_round_rate(hdmi->hdmi_clk, target);
-       unsigned long rate_error = rate > 0 ? abs(rate - target) : ULONG_MAX;
+       unsigned long target = PICOS2KHZ(mode->pixclock) * 1000, rate_error;
+       struct sh_mobile_hdmi_info *pdata = hdmi->dev->platform_data;
+
+       *hdmi_rate = clk_round_rate(hdmi->hdmi_clk, target);
+       if ((long)*hdmi_rate < 0)
+               *hdmi_rate = clk_get_rate(hdmi->hdmi_clk);
+
+       rate_error = (long)*hdmi_rate > 0 ? abs(*hdmi_rate - target) : ULONG_MAX;
+       if (rate_error && pdata->clk_optimize_parent)
+               rate_error = pdata->clk_optimize_parent(target, hdmi_rate, parent_rate);
+       else if (clk_get_parent(hdmi->hdmi_clk))
+               *parent_rate = clk_get_rate(clk_get_parent(hdmi->hdmi_clk));
 
        dev_dbg(hdmi->dev, "%u-%u-%u-%u x %u-%u-%u-%u\n",
                mode->left_margin, mode->xres,
@@ -697,14 +707,15 @@ static unsigned long sh_hdmi_rate_error(struct sh_hdmi *hdmi,
                mode->upper_margin, mode->yres,
                mode->lower_margin, mode->vsync_len);
 
-       dev_dbg(hdmi->dev, "\t@%lu(+/-%lu)Hz, e=%lu / 1000, r=%uHz\n", target,
-                rate_error, rate_error ? 10000 / (10 * target / rate_error) : 0,
-                mode->refresh);
+       dev_dbg(hdmi->dev, "\t@%lu(+/-%lu)Hz, e=%lu / 1000, r=%uHz, p=%luHz\n", target,
+               rate_error, rate_error ? 10000 / (10 * target / rate_error) : 0,
+               mode->refresh, *parent_rate);
 
        return rate_error;
 }
 
-static int sh_hdmi_read_edid(struct sh_hdmi *hdmi)
+static int sh_hdmi_read_edid(struct sh_hdmi *hdmi, unsigned long *hdmi_rate,
+                            unsigned long *parent_rate)
 {
        struct fb_var_screeninfo tmpvar;
        struct fb_var_screeninfo *var = &tmpvar;
@@ -754,11 +765,14 @@ static int sh_hdmi_read_edid(struct sh_hdmi *hdmi)
        for (i = 0, mode = hdmi->monspec.modedb;
             f_width && f_height && i < hdmi->monspec.modedb_len && !exact_match;
             i++, mode++) {
-               unsigned long rate_error = sh_hdmi_rate_error(hdmi, mode);
+               unsigned long rate_error;
 
                /* No interest in unmatching modes */
                if (f_width != mode->xres || f_height != mode->yres)
                        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
@@ -802,7 +816,7 @@ static int sh_hdmi_read_edid(struct sh_hdmi *hdmi)
 
                if (modelist) {
                        found = &modelist->mode;
-                       found_rate_error = sh_hdmi_rate_error(hdmi, found);
+                       found_rate_error = sh_hdmi_rate_error(hdmi, found, hdmi_rate, parent_rate);
                }
        }
 
@@ -810,10 +824,6 @@ static int sh_hdmi_read_edid(struct sh_hdmi *hdmi)
        if (!found)
                return -ENXIO;
 
-       dev_info(hdmi->dev, "Using %s mode %ux%u@%uHz (%luHz), clock error %luHz\n",
-                modelist ? "default" : "EDID", found->xres, found->yres,
-                found->refresh, PICOS2KHZ(found->pixclock) * 1000, found_rate_error);
-
        if ((found->xres == 720 && found->yres == 480) ||
            (found->xres == 1280 && found->yres == 720) ||
            (found->xres == 1920 && found->yres == 1080))
@@ -821,6 +831,11 @@ static int sh_hdmi_read_edid(struct sh_hdmi *hdmi)
        else
                hdmi->preprogrammed_mode = false;
 
+       dev_dbg(hdmi->dev, "Using %s %s mode %ux%u@%uHz (%luHz), clock error %luHz\n",
+               modelist ? "default" : "EDID", hdmi->preprogrammed_mode ? "VIC" : "external",
+               found->xres, found->yres, found->refresh,
+               PICOS2KHZ(found->pixclock) * 1000, found_rate_error);
+
        fb_videomode_to_var(&hdmi->var, found);
        sh_hdmi_external_video_param(hdmi);
 
@@ -972,39 +987,38 @@ static bool sh_hdmi_must_reconfigure(struct sh_hdmi *hdmi)
 
 /**
  * sh_hdmi_clk_configure() - set HDMI clock frequency and enable the clock
- * @hdmi:      driver context
- * @pixclock:  pixel clock period in picoseconds
- * return:     configured positive rate if successful
- *             0 if couldn't set the rate, but managed to enable the clock
- *             negative error, if couldn't enable the clock
+ * @hdmi:              driver context
+ * @hdmi_rate:         HDMI clock frequency in Hz
+ * @parent_rate:       if != 0 - set parent clock rate for optimal precision
+ * return:             configured positive rate if successful
+ *                     0 if couldn't set the rate, but managed to enable the
+ *                     clock, negative error, if couldn't enable the clock
  */
-static long sh_hdmi_clk_configure(struct sh_hdmi *hdmi, unsigned long pixclock)
+static long sh_hdmi_clk_configure(struct sh_hdmi *hdmi, unsigned long hdmi_rate,
+                                 unsigned long parent_rate)
 {
-       long rate;
+       struct sh_mobile_hdmi_info *pdata = hdmi->dev->platform_data;
        int ret;
 
-       rate = PICOS2KHZ(pixclock) * 1000;
-       rate = clk_round_rate(hdmi->hdmi_clk, rate);
-       if (rate > 0) {
-               ret = clk_set_rate(hdmi->hdmi_clk, rate);
+       if (parent_rate && clk_get_parent(hdmi->hdmi_clk)) {
+               ret = clk_set_rate(clk_get_parent(hdmi->hdmi_clk), parent_rate);
                if (ret < 0) {
-                       dev_warn(hdmi->dev, "Cannot set rate %ld: %d\n", rate, ret);
-                       rate = 0;
+                       dev_warn(hdmi->dev, "Cannot set parent rate %ld: %d\n", parent_rate, ret);
+                       hdmi_rate = clk_round_rate(hdmi->hdmi_clk, hdmi_rate);
                } else {
-                       dev_dbg(hdmi->dev, "HDMI set frequency %lu\n", rate);
+                       dev_dbg(hdmi->dev, "HDMI set parent frequency %lu\n", parent_rate);
                }
-       } else {
-               rate = 0;
-               dev_warn(hdmi->dev, "Cannot get suitable rate: %ld\n", rate);
        }
 
-       ret = clk_enable(hdmi->hdmi_clk);
+       ret = clk_set_rate(hdmi->hdmi_clk, hdmi_rate);
        if (ret < 0) {
-               dev_err(hdmi->dev, "Cannot enable clock: %d\n", ret);
-               return ret;
+               dev_warn(hdmi->dev, "Cannot set rate %ld: %d\n", hdmi_rate, ret);
+               hdmi_rate = 0;
+       } else {
+               dev_dbg(hdmi->dev, "HDMI set frequency %lu\n", hdmi_rate);
        }
 
-       return rate;
+       return hdmi_rate;
 }
 
 /* Hotplug interrupt occurred, read EDID */
@@ -1024,16 +1038,17 @@ static void sh_hdmi_edid_work_fn(struct work_struct *work)
        mutex_lock(&hdmi->mutex);
 
        if (hdmi->hp_state == HDMI_HOTPLUG_EDID_DONE) {
+               unsigned long parent_rate = 0, hdmi_rate;
+
                /* A device has been plugged in */
                pm_runtime_get_sync(hdmi->dev);
 
-               ret = sh_hdmi_read_edid(hdmi);
+               ret = sh_hdmi_read_edid(hdmi, &hdmi_rate, &parent_rate);
                if (ret < 0)
                        goto out;
 
                /* Reconfigure the clock */
-               clk_disable(hdmi->hdmi_clk);
-               ret = sh_hdmi_clk_configure(hdmi, hdmi->var.pixclock);
+               ret = sh_hdmi_clk_configure(hdmi, hdmi_rate, parent_rate);
                if (ret < 0)
                        goto out;
 
@@ -1166,13 +1181,22 @@ static int __init sh_hdmi_probe(struct platform_device *pdev)
                goto egetclk;
        }
 
-       /* Some arbitrary relaxed pixclock just to get things started */
-       rate = sh_hdmi_clk_configure(hdmi, 37037);
+       /* An arbitrary relaxed pixclock just to get things started: from standard 480p */
+       rate = clk_round_rate(hdmi->hdmi_clk, PICOS2KHZ(37037));
+       if (rate > 0)
+               rate = sh_hdmi_clk_configure(hdmi, rate, 0);
+
        if (rate < 0) {
                ret = rate;
                goto erate;
        }
 
+       ret = clk_enable(hdmi->hdmi_clk);
+       if (ret < 0) {
+               dev_err(hdmi->dev, "Cannot enable clock: %d\n", ret);
+               goto erate;
+       }
+
        dev_dbg(&pdev->dev, "Enabled HDMI clock at %luHz\n", rate);
 
        if (!request_mem_region(res->start, resource_size(res), dev_name(&pdev->dev))) {
@@ -1190,10 +1214,6 @@ static int __init sh_hdmi_probe(struct platform_device *pdev)
 
        platform_set_drvdata(pdev, hdmi);
 
-       /* Product and revision IDs are 0 in sh-mobile version */
-       dev_info(&pdev->dev, "Detected HDMI controller 0x%x:0x%x\n",
-                hdmi_read(hdmi, HDMI_PRODUCT_ID), hdmi_read(hdmi, HDMI_REVISION_ID));
-
        /* Set up LCDC callbacks */
        board_cfg = &pdata->lcd_chan->board_cfg;
        board_cfg->owner = THIS_MODULE;
@@ -1206,6 +1226,10 @@ static int __init sh_hdmi_probe(struct platform_device *pdev)
        pm_runtime_enable(&pdev->dev);
        pm_runtime_resume(&pdev->dev);
 
+       /* Product and revision IDs are 0 in sh-mobile version */
+       dev_info(&pdev->dev, "Detected HDMI controller 0x%x:0x%x\n",
+                hdmi_read(hdmi, HDMI_PRODUCT_ID), hdmi_read(hdmi, HDMI_REVISION_ID));
+
        ret = request_irq(irq, sh_hdmi_hotplug, 0,
                          dev_name(&pdev->dev), hdmi);
        if (ret < 0) {

diff --git a/include/video/sh_mobile_hdmi.h b/include/video/sh_mobile_hdmi.h
index 1e1aa54..b569329 100644 (file)
--- a/include/video/sh_mobile_hdmi.h
+++ b/include/video/sh_mobile_hdmi.h
@@ -13,6 +13,7 @@
 
 struct sh_mobile_lcdc_chan_cfg;
 struct device;
+struct clk;
 
 /*
  * flags format
@@ -33,6 +34,8 @@ struct sh_mobile_hdmi_info {
        struct sh_mobile_lcdc_chan_cfg  *lcd_chan;
        struct device                   *lcd_dev;
        unsigned int                     flags;
+       long (*clk_optimize_parent)(unsigned long target, unsigned long *best_freq,
+                                   unsigned long *parent_freq);
 };
 
 #endif