linux-kernel - Re: [PATCH 4/5] drm/msm/dp: Store each subblock in the io region

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Date:   Thu, 22 Jul 2021 20:13:46 +0000
From:   Stephen Boyd <swboyd@...omium.org>
To:     Abhinav Kumar <abhinavk@...eaurora.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Daniel Vetter <daniel@...ll.ch>,
        David Airlie <airlied@...ux.ie>,
        Rob Clark <robdclark@...il.com>,
        Rob Herring <robh+dt@...nel.org>, Sean Paul <sean@...rly.run>
Cc:     Kuogee Hsieh <khsieh@...eaurora.org>,
        Tanmay Shah <tanmay@...eaurora.org>,
        Chandan Uddaraju <chandanu@...eaurora.org>,
        linux-arm-msm@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        freedreno@...ts.freedesktop.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/5] drm/msm/dp: Store each subblock in the io region

Quoting Bjorn Andersson (2021-07-21 19:42:26)
> Not all platforms has DP_P0 at offset 0x1000 from the beginning of the
> DP block. So dss_io_data into representing each of the sub-regions, to

"So dss_io_data into" doesn't make sense to me. Is some word or words
missing?

> make it possible in the next patch to specify each of the sub-regions
> individually.
>
> Signed-off-by: Bjorn Andersson <bjorn.andersson@...aro.org>
> ---
>  drivers/gpu/drm/msm/dp/dp_catalog.c | 64 +++++++++--------------------
>  drivers/gpu/drm/msm/dp/dp_parser.c  | 30 ++++++++++++--
>  drivers/gpu/drm/msm/dp/dp_parser.h  | 10 ++++-
>  3 files changed, 54 insertions(+), 50 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.c b/drivers/gpu/drm/msm/dp/dp_parser.c
> index e68dacef547c..1a10901ae574 100644
> --- a/drivers/gpu/drm/msm/dp/dp_parser.c
> +++ b/drivers/gpu/drm/msm/dp/dp_parser.c
> @@ -11,6 +11,15 @@
>  #include "dp_parser.h"
>  #include "dp_reg.h"
>
> +#define DP_DEFAULT_AHB_OFFSET  0x0000
> +#define DP_DEFAULT_AHB_SIZE    0x0200
> +#define DP_DEFAULT_AUX_OFFSET  0x0200
> +#define DP_DEFAULT_AUX_SIZE    0x0200
> +#define DP_DEFAULT_LINK_OFFSET 0x0400
> +#define DP_DEFAULT_LINK_SIZE   0x0C00
> +#define DP_DEFAULT_P0_OFFSET   0x1000
> +#define DP_DEFAULT_P0_SIZE     0x0400
> +
>  static const struct dp_regulator_cfg sdm845_dp_reg_cfg = {
>         .num = 2,
>         .regs = {
> @@ -48,12 +57,25 @@ static int dp_parser_ctrl_res(struct dp_parser *parser)
>         struct dp_io *io = &parser->io;
>         struct dss_io_data *dss = &io->dp_controller;
>
> -       dss->base = dp_ioremap(pdev, 0, &dss->len);
> -       if (IS_ERR(dss->base)) {
> -               DRM_ERROR("unable to remap dp io region: %pe\n", dss->base);
> -               return PTR_ERR(dss->base);
> +       dss->ahb = dp_ioremap(pdev, 0, &dss->ahb_len);

So many layers of gunky goo!

> +       if (IS_ERR(dss->ahb)) {
> +               DRM_ERROR("unable to remap ahb region: %pe\n", dss->ahb);
> +               return PTR_ERR(dss->ahb);
>         }
>
> +       if (dss->ahb_len < DP_DEFAULT_P0_OFFSET + DP_DEFAULT_P0_SIZE) {
> +               DRM_ERROR("legacy memory region not large enough\n");
> +               return -EINVAL;
> +       }
> +
> +       dss->ahb_len = DP_DEFAULT_AHB_SIZE;
> +       dss->aux = dss->ahb + DP_DEFAULT_AUX_OFFSET;
> +       dss->aux_len = DP_DEFAULT_AUX_SIZE;
> +       dss->link = dss->ahb + DP_DEFAULT_LINK_OFFSET;
> +       dss->link_len = DP_DEFAULT_LINK_SIZE;
> +       dss->p0 = dss->ahb + DP_DEFAULT_P0_OFFSET;
> +       dss->p0_len = DP_DEFAULT_P0_SIZE;
> +
>         io->phy = devm_phy_get(&pdev->dev, "dp");
>         if (IS_ERR(io->phy))
>                 return PTR_ERR(io->phy);
> diff --git a/drivers/gpu/drm/msm/dp/dp_parser.h b/drivers/gpu/drm/msm/dp/dp_parser.h
> index dc62e70b1640..3266b529c090 100644
> --- a/drivers/gpu/drm/msm/dp/dp_parser.h
> +++ b/drivers/gpu/drm/msm/dp/dp_parser.h
> @@ -26,8 +26,14 @@ enum dp_pm_type {
>  };
>
>  struct dss_io_data {
> -       size_t len;
> -       void __iomem *base;
> +       void __iomem *ahb;
> +       size_t ahb_len;

Maybe make another struct and have a few of them here

	struct dss_io_region {
		void __iomem *base;
		size_t len;
	};

then the code reads as aux.base and aux.len and we know they're closely
related.

> +       void __iomem *aux;
> +       size_t aux_len;
> +       void __iomem *link;
> +       size_t link_len;
> +       void __iomem *p0;
> +       size_t p0_len;