From: dirk.behme@de•bosch.com (Dirk Behme)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH 3/3] ARM: imx6: Fix procedure to switch the parent of LDB_DI_CLK
Date: Tue, 10 Feb 2015 12:24:29 +0100 [thread overview]
Message-ID: <54D9EA6D.1020202@de.bosch.com> (raw)
In-Reply-To: <1420559265-7333-3-git-send-email-p.zabel@pengutronix.de>
On 06.01.2015 16:47, Philipp Zabel wrote:
> From: Fabio Estevam <fabio.estevam@freescale•com>
>
> Due to incorrect placement of the clock gate cell in the ldb_di[x]_clk tree,
> the glitchy parent mux of ldb_di[x]_clk can cause a glitch to enter the
> ldb_di_ipu_div divider. If the divider gets locked up, no ldb_di[x]_clk is
> generated, and the LVDS display will hang when the ipu_di_clk is sourced from
> ldb_di_clk.
>
> To fix the problem, both the new and current parent of the ldb_di_clk should
> be disabled before the switch. This patch ensures that correct steps are
> followed when ldb_di_clk parent is switched in the beginning of boot. The
> glitchy muxes are then registered as read-only. The clock parent can be selected
> using the assigned-clocks and assigned-clock-parents properties of the ccm
> device tree node:
>
> &clks {
> assigned-clocks = <&clks IMX6QDL_CLK_LDB_DI0_SEL>,
> <&clks IMX6QDL_CLK_LDB_DI1_SEL>;
> assigned-clock-parents = <&clks IMX6QDL_CLK_MMDC_CH1_AXI>,
> <&clks IMX6QDL_CLK_PLL5_VIDEO_DIV>;
> };
>
> Signed-off-by: Ranjani Vaidyanathan <Ranjani.Vaidyanathan@freescale•com>
> Signed-off-by: Fabio Estevam <fabio.estevam@freescale•com>
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix•de>
> ---
> arch/arm/mach-imx/clk-imx6q.c | 201 ++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 201 insertions(+)
>
> diff --git a/arch/arm/mach-imx/clk-imx6q.c b/arch/arm/mach-imx/clk-imx6q.c
> index 2e379fb..77aa7b17 100644
> --- a/arch/arm/mach-imx/clk-imx6q.c
> +++ b/arch/arm/mach-imx/clk-imx6q.c
...
> + /*
> + * The LDB_DI0/1_SEL muxes are registered read-only due to a hardware
> + * bug. Set the muxes to the requested values before registering the
> + * ldb_di_sel clocks.
> + */
> + if ((imx_get_soc_revision() != IMX_CHIP_REVISION_1_0) ||
> + cpu_is_imx6dl())
> + init_ldb_clks(np, base);
I've a hopefully simple understanding question regarding this if():
What does happen (or: has to be done) in the (non-existing) else case of
this if() statement?
E.g. how to configure the clocks for the imx_get_soc_revision() ==
IMX_CHIP_REVISION_1_0 case?
For the if() case, we can configure the clocks via the assigned-clocks
and assigned-clock-parents as described in the commit message. But how
to configure the clocks/muxes in the else case? To my understanding,
with the patch 2/3 [1] the clocks/muxes are configured to read only.
Sorry if I missed anything ;)
Many thanks,
Dirk
[1]
http://lists.infradead.org/pipermail/linux-arm-kernel/2015-January/313619.html
next prev parent reply other threads:[~2015-02-10 11:24 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-06 15:47 [PATCH 1/3] ARM: imx6: Mask mmdc_ch1 handshake for periph2_sel and mmdc_ch1_axi_podf Philipp Zabel
2015-01-06 15:47 ` [PATCH 2/3] ARM: imx6: Make the LDB_DI0 and LDB_DI1 clocks read-only Philipp Zabel
2015-01-06 15:47 ` [PATCH 3/3] ARM: imx6: Fix procedure to switch the parent of LDB_DI_CLK Philipp Zabel
2015-01-08 13:00 ` Shawn Guo
2015-01-15 16:54 ` Fabio Estevam
2015-01-16 9:28 ` Dirk Behme
2015-01-20 6:13 ` Shawn Guo
2015-01-20 6:00 ` Shawn Guo
2015-02-10 11:24 ` Dirk Behme [this message]
2015-02-10 15:31 ` Joshua Clayton
2015-02-10 17:21 ` Dirk Behme
2015-02-26 6:32 ` Dirk Behme
2015-02-26 8:51 ` Philipp Zabel
2015-01-07 16:26 ` [PATCH 1/3] ARM: imx6: Mask mmdc_ch1 handshake for periph2_sel and mmdc_ch1_axi_podf Fabio Estevam
2015-01-07 21:24 ` Christian Gmeiner
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