linux-kernel - Re: [PATCH v3 2/2] drm/tidss: Add support for AM625 DSS

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Date:   Thu, 28 Jul 2022 15:04:01 +0300
From:   Tomi Valkeinen <tomi.valkeinen@...asonboard.com>
To:     Aradhya Bhatia <a-bhatia1@...com>, Jyri Sarha <jyri.sarha@....fi>,
        Rob Herring <robh+dt@...nel.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>
Cc:     Nishanth Menon <nm@...com>, Vignesh Raghavendra <vigneshr@...com>,
        Rahul T R <r-ravikumar@...com>,
        Devarsh Thakkar <devarsht@...com>,
        DRI Development List <dri-devel@...ts.freedesktop.org>,
        Devicetree List <devicetree@...r.kernel.org>,
        Linux Kernel List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] drm/tidss: Add support for AM625 DSS

On 27/06/2022 18:12, Aradhya Bhatia wrote:
> Add support for the DSS IP on TI's new AM625 SoC in the tidss driver.
> 
> Signed-off-by: Aradhya Bhatia <a-bhatia1@...com>
> Reviewed-by: Rahul T R <r-ravikumar@...com>
> ---
>   drivers/gpu/drm/tidss/tidss_dispc.c | 56 ++++++++++++++++++++++++++++-
>   drivers/gpu/drm/tidss/tidss_dispc.h |  2 ++
>   drivers/gpu/drm/tidss/tidss_drv.c   |  1 +
>   3 files changed, 58 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/tidss/tidss_dispc.c b/drivers/gpu/drm/tidss/tidss_dispc.c
> index dae47853b728..f084f0688a54 100644
> --- a/drivers/gpu/drm/tidss/tidss_dispc.c
> +++ b/drivers/gpu/drm/tidss/tidss_dispc.c
> @@ -272,6 +272,55 @@ const struct dispc_features dispc_j721e_feats = {
>   	.vid_order = { 1, 3, 0, 2 },
>   };
>   
> +const struct dispc_features dispc_am625_feats = {
> +	.max_pclk_khz = {
> +		[DISPC_VP_DPI] = 165000,
> +		[DISPC_VP_OLDI] = 165000,
> +	},
> +
> +	.scaling = {
> +		.in_width_max_5tap_rgb = 1280,
> +		.in_width_max_3tap_rgb = 2560,
> +		.in_width_max_5tap_yuv = 2560,
> +		.in_width_max_3tap_yuv = 4096,
> +		.upscale_limit = 16,
> +		.downscale_limit_5tap = 4,
> +		.downscale_limit_3tap = 2,
> +		/*
> +		 * The max supported pixel inc value is 255. The value
> +		 * of pixel inc is calculated like this: 1+(xinc-1)*bpp.
> +		 * The maximum bpp of all formats supported by the HW
> +		 * is 8. So the maximum supported xinc value is 32,
> +		 * because 1+(32-1)*8 < 255 < 1+(33-1)*4.
> +		 */
> +		.xinc_max = 32,
> +	},
> +
> +	.subrev = DISPC_AM625,
> +
> +	.common = "common",
> +	.common_regs = tidss_am65x_common_regs,
> +
> +	.num_vps = 2,
> +	.vp_name = { "vp1", "vp2" },
> +	.ovr_name = { "ovr1", "ovr2" },
> +	.vpclk_name =  { "vp1", "vp2" },
> +	.vp_bus_type = { DISPC_VP_OLDI, DISPC_VP_DPI },

This looks correct, but with the two OLDI TXes, I think there will be 
some interesting issues.

The tidss_kms.c associates a DSS VP and a DT port, but that's no longer 
true if you add the ports for both OLDI TXes, as they both use the same 
VP. I think fixing that won't affect this patch, though, and merging 
this patch will, afaik, enable similar DSS functionality as we have for 
AM65x.

So, I think these two patches could be merged, or we could wait a bit 
until the OLDI situation becomes more clear. Up to you. In any case, for 
both patches:

Reviewed-by: Tomi Valkeinen <tomi.valkeinen@...asonboard.com>

  Tomi