The patch titled
mx3fb: introduce waveform configuration for Pixel Clock signal
has been removed from the -mm tree. Its filename was
mx3fb-introduce-waveform-configuration-for-pixel-clock-signal.patch
This patch was dropped because an updated version will be merged
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: mx3fb: introduce waveform configuration for Pixel Clock signal
From: Alberto Panizzo <maramaopercheseimorto@xxxxxxxxx>
Instead of static assignments for Pixel Clock waveform timings make it
machine configurable. This address an old problem posted here:
http://thread.gmane.org/gmane.linux.ports.arm.kernel/58185/focus=58285
In particular, the Armadillo 500 developing board is provided with a
digital to analogue converter chip that need a different than default
Pixel Clock waveform to perform the pixel conversion correctly. (Te DAC
is low CS enabled and need more time than a half pixelclock period to
perform the conversion)
This RFC address the problem modelling the pixelclock signal as a square
waveform where can be chosen the start and width for the high part of the
signal.
These parameters are expressed in sixteenths of the pixelclock period.
Why the number 16? Because I think it is the better trade off between the
maths offered by the hardware (DISP3_IF_CLK_[UP:DOWN]_WR are number with 2
fractional digits so the unity can be divided at least by 4 and the normal
configurations achieved with a 640x480 resolution is div = circa 4 with
400Mhz MCU clock) and the configuration needs (think that today this
timings cannot be configurable).
The code is developed to prevent regressions: if not configured
pix_clk_start and pix_clk_width, the driver probe function provide to
choose a configuration very similar (on my board equal) to the previous
one.
Signed-off-by: Alberto Panizzo <maramaopercheseimorto@xxxxxxxxx>
Cc: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
Cc: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
Cc: Krzysztof Helt <krzysztof.h1@xxxxx>
Cc: Alberto Panizzo <maramaopercheseimorto@xxxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm/plat-mxc/include/mach/mx3fb.h | 16 ++++++++++
drivers/video/mx3fb.c | 35 ++++++++++++++++++++---
2 files changed, 47 insertions(+), 4 deletions(-)
diff -puN arch/arm/plat-mxc/include/mach/mx3fb.h~mx3fb-introduce-waveform-configuration-for-pixel-clock-signal arch/arm/plat-mxc/include/mach/mx3fb.h
--- a/arch/arm/plat-mxc/include/mach/mx3fb.h~mx3fb-introduce-waveform-configuration-for-pixel-clock-signal
+++ a/arch/arm/plat-mxc/include/mach/mx3fb.h
@@ -33,6 +33,22 @@ struct mx3fb_platform_data {
const char *name;
const struct fb_videomode *mode;
int num_modes;
+
+ /*
+ * Timings configuration for the Pixel clock waveform:
+ * ___________
+ * _______| |_____ Pixel clock
+ * ^ ^ ^ ^
+ * |<--ts->|<---tw---->| |
+ * |<-----------Tc---------->|
+ *
+ * ts = (Tc * pix_clk_start) / 16
+ * tw = (Tc * pix_clk_width) / 16
+ *
+ * Constraint: ((pix_clk_start + pix_clk_width) / 16) <= 1
+ */
+ __u8 pix_clk_start;
+ __u8 pix_clk_width;
};
#endif
diff -puN drivers/video/mx3fb.c~mx3fb-introduce-waveform-configuration-for-pixel-clock-signal drivers/video/mx3fb.c
--- a/drivers/video/mx3fb.c~mx3fb-introduce-waveform-configuration-for-pixel-clock-signal
+++ a/drivers/video/mx3fb.c
@@ -241,6 +241,7 @@ struct mx3fb_data {
void __iomem *reg_base;
spinlock_t lock;
struct device *dev;
+ struct mx3fb_platform_data *pdata;
uint32_t h_start_width;
uint32_t v_start_width;
@@ -443,6 +444,7 @@ static int sdc_init_panel(struct mx3fb_d
uint16_t v_sync_width, uint16_t v_end_width,
struct ipu_di_signal_cfg sig)
{
+ struct mx3fb_platform_data *mx3fb_pdata = mx3fb->pdata;
unsigned long lock_flags;
uint32_t reg;
uint32_t old_conf;
@@ -506,6 +508,10 @@ static int sdc_init_panel(struct mx3fb_d
dev_dbg(mx3fb->dev,
"InitPanel() - Pixel clock divider less than 4\n");
div = 0x40;
+ } else if (div > 0xFFF) {
+ dev_dbg(mx3fb->dev,
+ "InitPanel() - Pixel clock divider greater than max\n");
+ div = 0xFFFF;
}
dev_dbg(mx3fb->dev, "pixel clk = %u, divider %u.%u\n",
@@ -514,11 +520,18 @@ static int sdc_init_panel(struct mx3fb_d
spin_lock_irqsave(&mx3fb->lock, lock_flags);
/*
- * DISP3_IF_CLK_DOWN_WR is half the divider value and 2 fraction bits
- * fewer. Subtract 1 extra from DISP3_IF_CLK_DOWN_WR based on timing
- * debug. DISP3_IF_CLK_UP_WR is 0
+ * Building DI_DISP3_TIME_CONF:
+ * DISP3_IF_CLK_PER_WR = div; (4 fractional digits)
+ * DISP3_IF_CLK_UP_WR [0:(DOWN_WR - 0.5)] (2 fractional digits)
+ * DISP3_IF_CLK_DOWN_WR [(UP_WR + 0.5):PER_WR] (2 fractional digits)
+ * using old_conf as buffer.
*/
- mx3fb_write_reg(mx3fb, (((div / 8) - 1) << 22) | div, DI_DISP3_TIME_CONF);
+ old_conf = div;
+ old_conf |= (((div * mx3fb_pdata->pix_clk_start) / 16) >> 2) << 12;
+ old_conf |= (((div * (mx3fb_pdata->pix_clk_start +
+ mx3fb_pdata->pix_clk_width)) / 16) >> 2) << 22;
+
+ mx3fb_write_reg(mx3fb, old_conf , DI_DISP3_TIME_CONF);
/* DI settings */
old_conf = mx3fb_read_reg(mx3fb, DI_DISP_IF_CONF) & 0x78FFFFFF;
@@ -1448,6 +1461,7 @@ static int mx3fb_probe(struct platform_d
dma_cap_mask_t mask;
struct dma_chan *chan;
struct dma_chan_request rq;
+ struct mx3fb_platform_data *pdata = pdev->dev.platform_data;
/*
* Display Interface (DI) and Synchronous Display Controller (SDC)
@@ -1463,6 +1477,19 @@ static int mx3fb_probe(struct platform_d
spin_lock_init(&mx3fb->lock);
+ /*
+ * If pixel clock configuration is not defined or misconfigured, fall
+ * through the default: rising edge at the beginning of the period and
+ * falling edge a bit before the half.
+ */
+ if ((!pdata->pix_clk_start && !pdata->pix_clk_width) ||
+ ((pdata->pix_clk_start + pdata->pix_clk_width) > 16) {
+ pr_debug("mx3fb: Default waveform for Pixel clock signal.\n");
+ pdata->pix_clk_start = 0;
+ pdata->pix_clk_width = 7;
+ }
+ mx3fb->pdata = pdata;
+
mx3fb->reg_base = ioremap(sdc_reg->start, resource_size(sdc_reg));
if (!mx3fb->reg_base) {
ret = -ENOMEM;
_
Patches currently in -mm which might be from maramaopercheseimorto@xxxxxxxxx are
origin.patch
linux-next.patch
checkpatchpl-warn-if-an-adding-line-introduce-spaces-before-tabs.patch
mx3fb-introduce-waveform-configuration-for-pixel-clock-signal.patch
w1-mxc_w1-move-probe-and-remove-to-the-dev-text-area.patch
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