Re: [PATCH 2/3] drm/msm/mdp5: move iommu_domain_alloc() call close to its usage

[Robin Murphy <robin.murphy@xxxxxxx>]

On 2022-05-03 14:30, Dmitry Baryshkov wrote:
> On Tue, 3 May 2022 at 13:57, Robin Murphy <robin.murphy@xxxxxxx> wrote:
> > On 2022-05-01 11:10, Dmitry Baryshkov wrote:
> > > Move iommu_domain_alloc() in front of adress space/IOMMU initialization.
> > > This allows us to drop final bits of struct mdp5_cfg_platform which
> > > remained from the pre-DT days.
> > >
> > > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> > > ---
> > >    drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.c | 16 ----------------
> > >    drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.h |  6 ------
> > >    drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c |  6 ++++--
> > >    3 files changed, 4 insertions(+), 24 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.c
> > > index 1bf9ff5dbabc..714effb967ff 100644
> > > --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.c
> > > +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.c
> > > @@ -1248,8 +1248,6 @@ static const struct mdp5_cfg_handler cfg_handlers_v3[] = {
> > >        { .revision = 3, .config = { .hw = &sdm630_config } },
> > >    };
> > >
> > > -static struct mdp5_cfg_platform *mdp5_get_config(struct platform_device *dev);
> > > -
> > >    const struct mdp5_cfg_hw *mdp5_cfg_get_hw_config(struct mdp5_cfg_handler *cfg_handler)
> > >    {
> > >        return cfg_handler->config.hw;
> > > @@ -1274,10 +1272,8 @@ struct mdp5_cfg_handler *mdp5_cfg_init(struct mdp5_kms *mdp5_kms,
> > >                uint32_t major, uint32_t minor)
> > >    {
> > >        struct drm_device *dev = mdp5_kms->dev;
> > > -     struct platform_device *pdev = to_platform_device(dev->dev);
> > >        struct mdp5_cfg_handler *cfg_handler;
> > >        const struct mdp5_cfg_handler *cfg_handlers;
> > > -     struct mdp5_cfg_platform *pconfig;
> > >        int i, ret = 0, num_handlers;
> > >
> > >        cfg_handler = kzalloc(sizeof(*cfg_handler), GFP_KERNEL);
> > > @@ -1320,9 +1316,6 @@ struct mdp5_cfg_handler *mdp5_cfg_init(struct mdp5_kms *mdp5_kms,
> > >        cfg_handler->revision = minor;
> > >        cfg_handler->config.hw = mdp5_cfg;
> > >
> > > -     pconfig = mdp5_get_config(pdev);
> > > -     memcpy(&cfg_handler->config.platform, pconfig, sizeof(*pconfig));
> > > -
> > >        DBG("MDP5: %s hw config selected", mdp5_cfg->name);
> > >
> > >        return cfg_handler;
> > > @@ -1333,12 +1326,3 @@ struct mdp5_cfg_handler *mdp5_cfg_init(struct mdp5_kms *mdp5_kms,
> > >
> > >        return ERR_PTR(ret);
> > >    }
> > > -
> > > -static struct mdp5_cfg_platform *mdp5_get_config(struct platform_device *dev)
> > > -{
> > > -     static struct mdp5_cfg_platform config = {};
> > > -
> > > -     config.iommu = iommu_domain_alloc(&platform_bus_type);
> > > -
> > > -     return &config;
> > > -}
> > > diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.h b/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.h
> > > index 6b03d7899309..c2502cc33864 100644
> > > --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.h
> > > +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_cfg.h
> > > @@ -104,14 +104,8 @@ struct mdp5_cfg_hw {
> > >        uint32_t max_clk;
> > >    };
> > >
> > > -/* platform config data (ie. from DT, or pdata) */
> > > -struct mdp5_cfg_platform {
> > > -     struct iommu_domain *iommu;
> > > -};
> > > -
> > >    struct mdp5_cfg {
> > >        const struct mdp5_cfg_hw *hw;
> > > -     struct mdp5_cfg_platform platform;
> > >    };
> > >
> > >    struct mdp5_kms;
> > > diff --git a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> > > index 9b7bbc3adb97..1c67c2c828cd 100644
> > > --- a/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> > > +++ b/drivers/gpu/drm/msm/disp/mdp5/mdp5_kms.c
> > > @@ -558,6 +558,7 @@ static int mdp5_kms_init(struct drm_device *dev)
> > >        struct msm_gem_address_space *aspace;
> > >        int irq, i, ret;
> > >        struct device *iommu_dev;
> > > +     struct iommu_domain *iommu;
> > >
> > >        ret = mdp5_init(to_platform_device(dev->dev), dev);
> > >
> > > @@ -601,14 +602,15 @@ static int mdp5_kms_init(struct drm_device *dev)
> > >        }
> > >        mdelay(16);
> > >
> > > -     if (config->platform.iommu) {
> > > +     iommu = iommu_domain_alloc(&platform_bus_type);
> >
> > To preempt the next change down the line as well, could this be
> > rearranged to work as iommu_domain_alloc(iommu_dev->bus)?
>
> I'd prefer to split this into the separate change, if you don't mind.

Oh, for sure, divide the patches however you see fit - I'm just hoping 
to save your time overall by getting all the IOMMU-related refactoring 
done now as a single series rather than risk me coming back and breaking 
things again in a few months :)

Cheers,
Robin.

> > > +     if (iommu) {
> > >                struct msm_mmu *mmu;
> > >
> > >                iommu_dev = &pdev->dev;
> > >                if (!dev_iommu_fwspec_get(iommu_dev))
> >
> > The fwspec helpers are more of an internal thing between the IOMMU
> > drivers and the respective firmware code - I'd rather that external API
> > users stuck consistently to using device_iommu_mapped() (it should give
> > the same result).
>
> Let me check that it works correctly and spin a v2 afterwards.
>
> > Otherwise, thanks for sorting this out!
> >
> > Robin.
> >
> > >                        iommu_dev = iommu_dev->parent;
> > >
> > > -             mmu = msm_iommu_new(iommu_dev, config->platform.iommu);
> > > +             mmu = msm_iommu_new(iommu_dev, iommu);
> > >
> > >                aspace = msm_gem_address_space_create(mmu, "mdp5",
> > >                        0x1000, 0x100000000 - 0x1000);