linux-kernel - Re: [PATCH 2/2] clk: imx: imx6ul: Fix csi clk gate register

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Date:   Thu, 26 Aug 2021 17:10:58 -0300
From:   Fabio Estevam <festevam@...il.com>
To:     Stefan Riedmueller <s.riedmueller@...tec.de>
Cc:     Abel Vesa <abel.vesa@....com>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>,
        Shawn Guo <shawnguo@...nel.org>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        NXP Linux Team <linux-imx@....com>,
        linux-clk <linux-clk@...r.kernel.org>,
        "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 
        <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] clk: imx: imx6ul: Fix csi clk gate register

Hi Stefan,

On Thu, Aug 26, 2021 at 12:20 PM Stefan Riedmueller
<s.riedmueller@...tec.de> wrote:
>
> According to the imx6ul Reference Manual the csi clk gate register is
> CCM_CCGR3 (offset 0x74) bit 0/1. For the imx6ull on the other hand the
> Reference Manual lists register CCM_CCGR2 (offset 0x70) bit 2/3 as the
> csi clk gate which is the current setting.
>
> Tests have shown though that the correct csi clk gate register for the
> imx6ull is actually CCM_CCGR3 bit 0/1 as well. Thus set the correct
> register for both platforms.
>
> Signed-off-by: Stefan Riedmueller <s.riedmueller@...tec.de>

I tested the series on an imx6ull-evk with an OV5640 sensor:

Tested-by: Fabio Estevam <festevam@...il.com>

but in my case, I did not see the problem even without your patch.

Most likely because the bootloader turned on the CSI clock.

> ---
>  drivers/clk/imx/clk-imx6ul.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/clk/imx/clk-imx6ul.c b/drivers/clk/imx/clk-imx6ul.c
> index 206e4c43f68f..5dd222fab01b 100644
> --- a/drivers/clk/imx/clk-imx6ul.c
> +++ b/drivers/clk/imx/clk-imx6ul.c
> @@ -380,7 +380,6 @@ static void __init imx6ul_clocks_init(struct device_node *ccm_node)
>                 hws[IMX6ULL_CLK_ESAI_IPG]       = imx_clk_hw_gate2_shared("esai_ipg",   "ahb",          base + 0x70,    0, &share_count_esai);
>                 hws[IMX6ULL_CLK_ESAI_MEM]       = imx_clk_hw_gate2_shared("esai_mem",   "ahb",          base + 0x70,    0, &share_count_esai);
>         }
> -       hws[IMX6UL_CLK_CSI]             = imx_clk_hw_gate2("csi",               "csi_podf",             base + 0x70,    2);
>         hws[IMX6UL_CLK_I2C1]            = imx_clk_hw_gate2("i2c1",              "perclk",       base + 0x70,    6);
>         hws[IMX6UL_CLK_I2C2]            = imx_clk_hw_gate2("i2c2",              "perclk",       base + 0x70,    8);
>         hws[IMX6UL_CLK_I2C3]            = imx_clk_hw_gate2("i2c3",              "perclk",       base + 0x70,    10);
> @@ -391,6 +390,7 @@ static void __init imx6ul_clocks_init(struct device_node *ccm_node)
>         hws[IMX6UL_CLK_PXP]             = imx_clk_hw_gate2("pxp",               "axi",          base + 0x70,    30);
>
>         /* CCGR3 */

It would be nice to put a comment here explaining the imx6ull
Reference Manual mismatch.

Maybe Abel could help to check internally at NXP?

> +       hws[IMX6UL_CLK_CSI]             = imx_clk_hw_gate2("csi",       "csi_podf",     base + 0x74,    0);

Thanks