[PATCH 2/2] OMAPDSS: HDMI: Disable HDMI DDC internal pull up

[PATCH 2/2] OMAPDSS: HDMI: Disable HDMI DDC internal pull up

[mythripk]

From: Mythri P K <mythripk@ti.com>

Disables the internal pull resistor for SDA and SCL enabled by
default as there are expernal pull up's to avoid the EDID read failure.

Signed-off-by: Ricardo Salveti de Araujo <ricardo.salveti@linaro.org>
Signed-off-by: Mythri P K <mythripk@ti.com>
---
 arch/arm/mach-omap2/display.c |   18 ++++++++++++++++++
 1 files changed, 18 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-omap2/display.c b/arch/arm/mach-omap2/display.c
index f6590b9..3e70ef8 100644
--- a/arch/arm/mach-omap2/display.c
+++ b/arch/arm/mach-omap2/display.c
@@ -106,6 +106,9 @@ static const struct omap_dss_hwmod_data omap4_dss_hwmod_data[] __initdata = {
 
 static void omap4_hdmi_mux_pads(void)
 {
+	u32 reg;
+	u16 control_i2c_1;
+
 	/* PAD0_HDMI_HPD_PAD1_HDMI_CEC */
 	omap_mux_init_signal("hdmi_hpd",
 			OMAP_PIN_INPUT_PULLUP);
@@ -116,6 +119,21 @@ static void omap4_hdmi_mux_pads(void)
 			OMAP_PIN_INPUT_PULLUP);
 	omap_mux_init_signal("hdmi_ddc_sda",
 			OMAP_PIN_INPUT_PULLUP);
+
+	/*
+	 * CONTROL_I2C_1: HDMI_DDC_SDA_PULLUPRESX (bit 28) and
+	 * HDMI_DDC_SCL_PULLUPRESX (bit 24) are set to disable
+	 * internal pull up resistor - This is a change needed in
+	 * OMAP4460 and OMAP4430 ES2.3 as the external pull up
+	 * are present. This is needed to avoid EDID read failure.
+	 */
+	if (cpu_is_omap446x() || (omap_rev() > OMAP4430_REV_ES2_2)) {
+		control_i2c_1 = OMAP4_CTRL_MODULE_PAD_CORE_CONTROL_I2C_1;
+		reg = omap4_ctrl_pad_readl(control_i2c_1);
+		reg |= (OMAP4_HDMI_DDC_SDA_PULLUPRESX_MASK |
+		OMAP4_HDMI_DDC_SCL_PULLUPRESX_MASK);
+		omap4_ctrl_pad_writel(reg, control_i2c_1);
+	}
 }
 
 static int omap4_dsi_mux_pads(int dsi_id, unsigned lanes)
-- 
1.7.5.4

Re: [PATCH 2/2] OMAPDSS: HDMI: Disable HDMI DDC internal pull up

[Tomi Valkeinen]

On Fri, 2011-10-21 at 14:57 +0530, mythripk@ti.com wrote:
> From: Mythri P K <mythripk@ti.com>
> 
> Disables the internal pull resistor for SDA and SCL enabled by
> default as there are expernal pull up's to avoid the EDID read failure.

What do you mean with external pull up? Outside OMAP? Then it's a board
specific feature, isn't it, and not related to the OMAP version?

 Tomi

Re: [PATCH 2/2] OMAPDSS: HDMI: Disable HDMI DDC internal pull up

[K, Mythri P]

Hi,

On Fri, Oct 21, 2011 at 4:49 PM, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:
> On Fri, 2011-10-21 at 14:57 +0530, mythripk@ti.com wrote:
>> From: Mythri P K <mythripk@ti.com>
>>
>> Disables the internal pull resistor for SDA and SCL enabled by
>> default as there are expernal pull up's to avoid the EDID read failure.
>
> What do you mean with external pull up? Outside OMAP? Then it's a board
> specific feature, isn't it, and not related to the OMAP version?
yes it is not specific to OMAP. SDP/Panda  boards OMAP 4430 version
ES2.3 and 4460 have this  board change, but as there is not separate
board file as such for these boards i have added the check as above.Do
you have any other idea?

Thanks and regards,
Mythri.
>
>  Tomi
>
>
>
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Re: [PATCH 2/2] OMAPDSS: HDMI: Disable HDMI DDC internal pull up

[Tomi Valkeinen]

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On Tue, 2011-10-25 at 15:05 +0530, K, Mythri P wrote:
> Hi,
> 
> On Fri, Oct 21, 2011 at 4:49 PM, Tomi Valkeinen <tomi.valkeinen@ti.com> wrote:
> > On Fri, 2011-10-21 at 14:57 +0530, mythripk@ti.com wrote:
> >> From: Mythri P K <mythripk@ti.com>
> >>
> >> Disables the internal pull resistor for SDA and SCL enabled by
> >> default as there are expernal pull up's to avoid the EDID read failure.
> >
> > What do you mean with external pull up? Outside OMAP? Then it's a board
> > specific feature, isn't it, and not related to the OMAP version?
> yes it is not specific to OMAP. SDP/Panda  boards OMAP 4430 version
> ES2.3 and 4460 have this  board change, but as there is not separate
> board file as such for these boards i have added the check as above.Do
> you have any other idea?

Well, in that case the code is obviously wrong. The choice whether to
enable or disable the pull up has to come from the board file.

 Tomi


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