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fbdev: sh_mobile_hdmi: add support for more precise HDMI clock config…
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…uration

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>
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Guennadi Liakhovetski authored and Paul Mundt committed Nov 10, 2010
1 parent 5fd284e commit c36940e
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Showing 2 changed files with 71 additions and 44 deletions.
112 changes: 68 additions & 44 deletions drivers/video/sh_mobile_hdmi.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -685,26 +685,37 @@ 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,
mode->right_margin, mode->hsync_len,
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;
Expand Down Expand Up @@ -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
Expand Down Expand Up @@ -802,25 +816,26 @@ 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);
}
}

/* No cookie today */
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))
hdmi->preprogrammed_mode = true;
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);

Expand Down Expand Up @@ -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 */
Expand All @@ -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;

Expand Down Expand Up @@ -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))) {
Expand All @@ -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;
Expand All @@ -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) {
Expand Down
3 changes: 3 additions & 0 deletions include/video/sh_mobile_hdmi.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,7 @@

struct sh_mobile_lcdc_chan_cfg;
struct device;
struct clk;

/*
* flags format
Expand All @@ -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

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