Re: [Freedreno] [PATCH] drm/msm: less magic numbers in msm_mdss_enable

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On Thu, 2 Jun 2022 at 21:18, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
>
>
>
> On 6/1/2022 1:04 PM, Dmitry Baryshkov wrote:
> > On Wed, 1 Jun 2022 at 20:38, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
> >>
> >>
> >>
> >> On 6/1/2022 2:46 AM, Dmitry Baryshkov wrote:
> >>> On Wed, 1 Jun 2022 at 01:01, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
> >>>> On 5/31/2022 5:18 AM, Dmitry Baryshkov wrote:
> >>>>> Replace magic register writes in msm_mdss_enable() with version that
> >>>>> contains less magic and more variable names that can be traced back to
> >>>>> the dpu_hw_catalog or the downstream dtsi files.
> >>>>>
> >>>>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> >>>>> ---
> >>>>>     drivers/gpu/drm/msm/msm_mdss.c | 79 ++++++++++++++++++++++++++++++----
> >>>>>     1 file changed, 71 insertions(+), 8 deletions(-)
> >>>>>
> >>>>> diff --git a/drivers/gpu/drm/msm/msm_mdss.c b/drivers/gpu/drm/msm/msm_mdss.c
> >>>>> index 0454a571adf7..2a48263cd1b5 100644
> >>>>> --- a/drivers/gpu/drm/msm/msm_mdss.c
> >>>>> +++ b/drivers/gpu/drm/msm/msm_mdss.c
> >>>>> @@ -21,6 +21,7 @@
> >>>>>     #define HW_REV                              0x0
> >>>>>     #define HW_INTR_STATUS                      0x0010
> >>>>>
> >>>>> +#define UBWC_DEC_HW_VERSION          0x58
> >>>>>     #define UBWC_STATIC                 0x144
> >>>>>     #define UBWC_CTRL_2                 0x150
> >>>>>     #define UBWC_PREDICTION_MODE                0x154
> >>>>> @@ -132,9 +133,63 @@ static int _msm_mdss_irq_domain_add(struct msm_mdss *msm_mdss)
> >>>>>         return 0;
> >>>>>     }
> >>>>>
> >>>>> +#define UBWC_1_0 0x10000000
> >>>>> +#define UBWC_2_0 0x20000000
> >>>>> +#define UBWC_3_0 0x30000000
> >>>>> +#define UBWC_4_0 0x40000000
> >>>>> +
> >>>>> +static void msm_mdss_setup_ubwc_dec_20(struct msm_mdss *msm_mdss,
> >>>>> +                                    u32 ubwc_static)
> >>>>> +{
> >>>>> +     writel_relaxed(ubwc_static, msm_mdss->mmio + UBWC_STATIC);
> >>>>> +}
> >>>>> +
> >>>>> +static void msm_mdss_setup_ubwc_dec_30(struct msm_mdss *msm_mdss,
> >>>>> +                                    unsigned int ubwc_version,
> >>>>> +                                    u32 ubwc_swizzle,
> >>>>> +                                    u32 highest_bank_bit,
> >>>>> +                                    u32 macrotile_mode)
> >>>>> +{
> >>>>> +     u32 value = (ubwc_swizzle & 0x1) |
> >>>>> +                 (highest_bank_bit & 0x3) << 4 |
> >>>>> +                 (macrotile_mode & 0x1) << 12;
> >>>>> +
> >>>>> +     if (ubwc_version == UBWC_3_0)
> >>>>> +             value |= BIT(10);
> >>>>> +
> >>>>> +     if (ubwc_version == UBWC_1_0)
> >>>>> +             value |= BIT(8);
> >>>>> +
> >>>>> +     writel_relaxed(value, msm_mdss->mmio + UBWC_STATIC);
> >>>>> +}
> >>>>> +
> >>>>> +static void msm_mdss_setup_ubwc_dec_40(struct msm_mdss *msm_mdss,
> >>>>> +                                    unsigned int ubwc_version,
> >>>>> +                                    u32 ubwc_swizzle,
> >>>>> +                                    u32 ubwc_static,
> >>>>> +                                    u32 highest_bank_bit,
> >>>>> +                                    u32 macrotile_mode)
> >>>>> +{
> >>>>> +     u32 value = (ubwc_swizzle & 0x7) |
> >>>>> +                 (ubwc_static & 0x1) << 3 |
> >>>>> +                 (highest_bank_bit & 0x7) << 4 |
> >>>>> +                 (macrotile_mode & 0x1) << 12;
> >>>>> +
> >>>>> +     writel_relaxed(value, msm_mdss->mmio + UBWC_STATIC);
> >>>>> +
> >>>>> +     if (ubwc_version == UBWC_3_0) {
> >>>>> +             writel_relaxed(1, msm_mdss->mmio + UBWC_CTRL_2);
> >>>>> +             writel_relaxed(0, msm_mdss->mmio + UBWC_PREDICTION_MODE);
> >>>>> +     } else {
> >>>>> +             writel_relaxed(2, msm_mdss->mmio + UBWC_CTRL_2);
> >>>>> +             writel_relaxed(1, msm_mdss->mmio + UBWC_PREDICTION_MODE);
> >>>>> +     }
> >>>>> +}
> >>>>> +
> >>>>
> >>>> Is it possible to unify the above functions by having the internal
> >>>> ubwc_version checks?
> >>>
> >>> Note, it's not the ubwc_version, it is the ubwc_dec_hw_version. And
> >>> also different functions take different sets of arguments.
> >>>
> >>>> It seems like msm_mdss_setup_ubwc_dec_xxx can keep growing.
> >>>>
> >>>> I have not looked into each bit programming but from the top level so
> >>>> feel free to correct if wrong but it seems both do write UBWC_STATIC
> >>>> (different values based on different UBWC versions) and write some extra
> >>>> registers based on version
> >>>
> >>> This is what both the current code and the downstream do. See
> >>> https://github.com/MiCode/Xiaomi_Kernel_OpenSource/blob/zeus-s-oss/techpack/display-drivers/msm/sde/sde_hw_top.c#L312
> >>>
> >>
> >> Thanks for pointing to the downstream method for this,
> >>
> >> This is exactly what i was also suggesting to do when I mentioned
> >> unifying the above functions.
> >>
> >> So instead of having a separate function for each version why not handle
> >> all the versions in the same function like what the link you have shown
> >> does.
> >
> > I wouldn't like that. The downstream uses hw_catalog to pass all
> > possible parameters. We do not, so we'd have a whole set of artificial
> > values.
> >
>
> Now that you brought that up, why cannot even upstream dpu start using
> catalog for ubwc settings?

Because msm_mdss lives out of disp/dpu1. And using the disp/dpu1 for
it would be an inversion of dependencies.
I like the fact that msm_mdss is independent of mdp/dpu drivers and I
do not want to add such dependency.

>
> /* struct dpu_mdp_cfg : MDP TOP-BLK instance info
>   * @id:                index identifying this block
>   * @base:              register base offset to mdss
>   * @features           bit mask identifying sub-blocks/features
>   * @highest_bank_bit:  UBWC parameter
>   * @ubwc_static:       ubwc static configuration
>   * @ubwc_swizzle:      ubwc default swizzle setting
>   * @clk_ctrls          clock control register definition
>   */
> struct dpu_mdp_cfg {
>      DPU_HW_BLK_INFO;
>      u32 highest_bank_bit;
>      u32 ubwc_swizzle;
>      struct dpu_clk_ctrl_reg clk_ctrls[DPU_CLK_CTRL_MAX];
> };
>
> We already do seem to have a couple of parameters. have to add the others.
>
> That way the number of functions wont keep growing.
>
> >>
> >>>>
> >>>>>     static int msm_mdss_enable(struct msm_mdss *msm_mdss)
> >>>>>     {
> >>>>>         int ret;
> >>>>> +     u32 hw_rev;
> >>>>>
> >>>>>         ret = clk_bulk_prepare_enable(msm_mdss->num_clocks, msm_mdss->clocks);
> >>>>>         if (ret) {
> >>>>> @@ -149,26 +204,34 @@ static int msm_mdss_enable(struct msm_mdss *msm_mdss)
> >>>>>         if (msm_mdss->is_mdp5)
> >>>>>                 return 0;
> >>>>>
> >>>>> +     hw_rev = readl_relaxed(msm_mdss->mmio + HW_REV);
> >>>>> +     dev_info(msm_mdss->dev, "HW_REV: 0x%x\n", hw_rev);
> >>>>> +     dev_info(msm_mdss->dev, "UBWC_DEC_HW_VERSION: 0x%x\n",
> >>>>> +             readl_relaxed(msm_mdss->mmio + UBWC_DEC_HW_VERSION));
> >>>>
> >>>> we are already printing the HW version here
> >>>>
> >>>> https://gitlab.freedesktop.org/drm/msm/-/blob/msm-next/drivers/gpu/drm/msm/disp/dpu1/dpu_kms.c#L1096
> >>>>
> >>>> Do you want to remove that print then? May be. Let me take a look.
> >>>
> >>> [skipped]
> >>>
> >
> >
> >



-- 
With best wishes
Dmitry



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