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[1/3] ARM: imx6: Mask mmdc_ch1 handshake for periph2_sel and mmdc_ch1_axi_podf

Message ID 1420559265-7333-1-git-send-email-p.zabel@pengutronix.de (mailing list archive)
State New, archived
Headers show

Commit Message

Philipp Zabel Jan. 6, 2015, 3:47 p.m. UTC
MMDC CH1 is not used on i.MX6Q, so the handshake needed to change the parent
of periph2_sel or the divider of mmdc_ch1_axi_podf will never succeed.
Disable the handshake mechanism to allow changing the frequency of mmdc_ch1_axi,
allowing to use it as a possible source for the LDB DI clock.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
---
 arch/arm/mach-imx/clk-imx6q.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

Comments

Fabio Estevam Jan. 7, 2015, 4:26 p.m. UTC | #1
Hi Philipp,

On Tue, Jan 6, 2015 at 1:47 PM, Philipp Zabel <p.zabel@pengutronix.de> wrote:
> MMDC CH1 is not used on i.MX6Q, so the handshake needed to change the parent
> of periph2_sel or the divider of mmdc_ch1_axi_podf will never succeed.
> Disable the handshake mechanism to allow changing the frequency of mmdc_ch1_axi,
> allowing to use it as a possible source for the LDB DI clock.
>
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>

Thanks for working on this series. It looks great.

I am adding Christian on Cc as he could reproduce the bug quickly on
his setup. Maybe he could give his Tested-by?

On my board it takes a long time to reproduce the ldb clock lock-up issue.

Thanks
Christian Gmeiner Jan. 7, 2015, 9:24 p.m. UTC | #2
Hi all

> On Tue, Jan 6, 2015 at 1:47 PM, Philipp Zabel <p.zabel@pengutronix.de> wrote:
>> MMDC CH1 is not used on i.MX6Q, so the handshake needed to change the parent
>> of periph2_sel or the divider of mmdc_ch1_axi_podf will never succeed.
>> Disable the handshake mechanism to allow changing the frequency of mmdc_ch1_axi,
>> allowing to use it as a possible source for the LDB DI clock.
>>
>> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
>
> Thanks for working on this series. It looks great.
>
> I am adding Christian on Cc as he could reproduce the bug quickly on
> his setup. Maybe he could give his Tested-by?
>

I will have a look at it as I am able to reproduce this problem in
less then 10 minutes. I am not
sure if I find time during this week, but I try my best.

greets
--
Christian Gmeiner, MSc

https://soundcloud.com/christian-gmeiner
diff mbox

Patch

diff --git a/arch/arm/mach-imx/clk-imx6q.c b/arch/arm/mach-imx/clk-imx6q.c
index 5951660..f2e7cfc 100644
--- a/arch/arm/mach-imx/clk-imx6q.c
+++ b/arch/arm/mach-imx/clk-imx6q.c
@@ -120,6 +120,19 @@  static unsigned int share_count_ssi1;
 static unsigned int share_count_ssi2;
 static unsigned int share_count_ssi3;
 
+#define CCM_CCDR		0x04
+
+#define CCDR_MMDC_CH1_MASK	BIT(16)
+
+static void __init imx6q_mmdc_ch1_mask_handshake(void __iomem *ccm_base)
+{
+	unsigned int reg;
+
+	reg = readl_relaxed(ccm_base + CCM_CCDR);
+	reg |= CCDR_MMDC_CH1_MASK;
+	writel_relaxed(reg, ccm_base + CCM_CCDR);
+}
+
 static void __init imx6q_clocks_init(struct device_node *ccm_node)
 {
 	struct device_node *np;
@@ -261,6 +274,7 @@  static void __init imx6q_clocks_init(struct device_node *ccm_node)
 	WARN_ON(!base);
 
 	imx6q_pm_set_ccm_base(base);
+	imx6q_mmdc_ch1_mask_handshake(base);
 
 	/*                                              name                reg       shift width parent_names     num_parents */
 	clk[IMX6QDL_CLK_STEP]             = imx_clk_mux("step",	            base + 0xc,  8,  1, step_sels,	   ARRAY_SIZE(step_sels));