linux-kernel - Re: [PATCH 16/19] media: i2c: ds90ub960: Enable SSCG for UB9702

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Message-ID: <Z4fFr-ZgCIFT_PTx@kekkonen.localdomain>
Date: Wed, 15 Jan 2025 14:26:55 +0000
From: Sakari Ailus <sakari.ailus@...ux.intel.com>
To: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
Cc: Mauro Carvalho Chehab <mchehab@...nel.org>, linux-media@...r.kernel.org,
	linux-kernel@...r.kernel.org, Devarsh Thakkar <devarsht@...com>,
	Jai Luthra <jai.luthra@...asonboard.com>
Subject: Re: [PATCH 16/19] media: i2c: ds90ub960: Enable SSCG for UB9702

Moi,

On Fri, Jan 10, 2025 at 11:14:16AM +0200, Tomi Valkeinen wrote:
> From: Jai Luthra <jai.luthra@...asonboard.com>
> 
> UB9702 supports spread-spectrum clock generation for the back-channel
> clock, which is futher used by serializers in synchronous mode to
> generate the forward-channel clock, which can help reduce peak EMI
> energy. The SSCG is common to all RX ports, so it can only be used if
> all the ports are in the same mode.
> 
> Add basic support for SSCG by adding a module parameter to enable the
> SSCG. The SSCG uses hardcoded configurationg, with 0.5% center-spread at
> 33kHz modulation rate. See datasheet if different configuration is
> required.
> 
> Signed-off-by: Jai Luthra <jai.luthra@...asonboard.com>
> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
> ---
>  drivers/media/i2c/ds90ub960.c | 102 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 102 insertions(+)
> 
> diff --git a/drivers/media/i2c/ds90ub960.c b/drivers/media/i2c/ds90ub960.c
> index f6d6c2fe12cd..a534d077f045 100644
> --- a/drivers/media/i2c/ds90ub960.c
> +++ b/drivers/media/i2c/ds90ub960.c
> @@ -52,6 +52,10 @@
>  #include <media/v4l2-fwnode.h>
>  #include <media/v4l2-subdev.h>
>  
> +static bool ub960_enable_sscg;
> +module_param_named(enable_sscg, ub960_enable_sscg, bool, 0644);
> +MODULE_PARM_DESC(enable_sscg, "Enable SSCG (if available)");

Shouldn't this come from DT instead?

-- 
Terveisin,

Sakari Ailus