On Fri, 2 Sept 2022 at 21:07, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
>
>
>
> On 9/1/2022 11:06 PM, Dmitry Baryshkov wrote:
> >
> >
> > On 2 September 2022 03:24:17 GMT+03:00, Abhinav Kumar <quic_abhinavk@xxxxxxxxxxx> wrote:
> >>
> >>
> >> On 6/20/2022 2:30 PM, Dmitry Baryshkov wrote:
> >>> To let the probe function bail early if any of the resources is
> >>> unavailable, move resource allocattion from kms_init directly to the
> >>> probe callback. While we are at it, replace irq_of_parse_and_map() with
> >>> platform_get_irq().
> >>>
> >>> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@xxxxxxxxxx>
> >>> ---
> >>> drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c | 107 +++++++++++------------
> >>> 1 file changed, 51 insertions(+), 56 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> >>> index 41dc60784847..6499713eccf6 100644
> >>> --- a/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> >>> +++ b/drivers/gpu/drm/msm/disp/mdp4/mdp4_kms.c
> >>> @@ -139,8 +139,6 @@ static void mdp4_destroy(struct msm_kms *kms)
> >>> pm_runtime_disable(dev);
> >>> mdp_kms_destroy(&mdp4_kms->base);
> >>> -
> >>> - kfree(mdp4_kms);
> >>> }
> >>> static const struct mdp_kms_funcs kms_funcs = {
> >>> @@ -383,57 +381,27 @@ static int mdp4_kms_init(struct drm_device *dev)
> >>> {
> >>> struct platform_device *pdev = to_platform_device(dev->dev);
> >>> struct msm_drm_private *priv = dev->dev_private;
> >>> - struct mdp4_kms *mdp4_kms;
> >>> + struct mdp4_kms *mdp4_kms = to_mdp4_kms(to_mdp_kms(priv->kms));
> >>> struct msm_kms *kms = NULL;
> >>> struct iommu_domain *iommu;
> >>> struct msm_gem_address_space *aspace;
> >>> - int irq, ret;
> >>> + int ret;
> >>> u32 major, minor;
> >>> unsigned long max_clk;
> >>> /* TODO: Chips that aren't apq8064 have a 200 Mhz max_clk */
> >>> max_clk = 266667000;
> >>> - mdp4_kms = kzalloc(sizeof(*mdp4_kms), GFP_KERNEL);
> >>> - if (!mdp4_kms) {
> >>> - DRM_DEV_ERROR(dev->dev, "failed to allocate kms\n");
> >>> - return -ENOMEM;
> >>> - }
> >>> -
> >>> ret = mdp_kms_init(&mdp4_kms->base, &kms_funcs);
> >>> if (ret) {
> >>> DRM_DEV_ERROR(dev->dev, "failed to init kms\n");
> >>> goto fail;
> >>> }
> >>> - priv->kms = &mdp4_kms->base.base;
> >>> kms = priv->kms;
> >>> mdp4_kms->dev = dev;
> >>> - mdp4_kms->mmio = msm_ioremap(pdev, NULL);
> >>> - if (IS_ERR(mdp4_kms->mmio)) {
> >>> - ret = PTR_ERR(mdp4_kms->mmio);
> >>> - goto fail;
> >>> - }
> >>> -
> >>> - irq = platform_get_irq(pdev, 0);
> >>> - if (irq < 0) {
> >>> - ret = irq;
> >>> - DRM_DEV_ERROR(dev->dev, "failed to get irq: %d\n", ret);
> >>> - goto fail;
> >>> - }
> >>> -
> >>> - kms->irq = irq;
> >>> -
> >>> - /* NOTE: driver for this regulator still missing upstream.. use
> >>> - * _get_exclusive() and ignore the error if it does not exist
> >>> - * (and hope that the bootloader left it on for us)
> >>> - */
> >>> - mdp4_kms->vdd = devm_regulator_get_exclusive(&pdev->dev, "vdd");
> >>> - if (IS_ERR(mdp4_kms->vdd))
> >>> - mdp4_kms->vdd = NULL;
> >>> -
> >>> if (mdp4_kms->vdd) {
> >>> ret = regulator_enable(mdp4_kms->vdd);
> >>> if (ret) {
> >>> @@ -442,24 +410,6 @@ static int mdp4_kms_init(struct drm_device *dev)
> >>> }
> >>> }
> >>> - mdp4_kms->clk = devm_clk_get(&pdev->dev, "core_clk");
> >>> - if (IS_ERR(mdp4_kms->clk)) {
> >>> - DRM_DEV_ERROR(dev->dev, "failed to get core_clk\n");
> >>> - ret = PTR_ERR(mdp4_kms->clk);
> >>> - goto fail;
> >>> - }
> >>> -
> >>> - mdp4_kms->pclk = devm_clk_get(&pdev->dev, "iface_clk");
> >>> - if (IS_ERR(mdp4_kms->pclk))
> >>> - mdp4_kms->pclk = NULL;
> >>> -
> >>> - mdp4_kms->axi_clk = devm_clk_get(&pdev->dev, "bus_clk");
> >>> - if (IS_ERR(mdp4_kms->axi_clk)) {
> >>> - DRM_DEV_ERROR(dev->dev, "failed to get axi_clk\n");
> >>> - ret = PTR_ERR(mdp4_kms->axi_clk);
> >>> - goto fail;
> >>> - }
> >>> -
> >>> clk_set_rate(mdp4_kms->clk, max_clk);
> >>> read_mdp_hw_revision(mdp4_kms, &major, &minor);
> >>> @@ -474,10 +424,9 @@ static int mdp4_kms_init(struct drm_device *dev)
> >>> mdp4_kms->rev = minor;
> >>> if (mdp4_kms->rev >= 2) {
> >>> - mdp4_kms->lut_clk = devm_clk_get(&pdev->dev, "lut_clk");
> >>> - if (IS_ERR(mdp4_kms->lut_clk)) {
> >>> + if (!mdp4_kms->lut_clk) {
> >>> DRM_DEV_ERROR(dev->dev, "failed to get lut_clk\n");
> >>> - ret = PTR_ERR(mdp4_kms->lut_clk);
> >>> + ret = -ENODEV;
> >>> goto fail;
> >>> }
> >>> clk_set_rate(mdp4_kms->lut_clk, max_clk);
> >>> @@ -560,7 +509,53 @@ static const struct dev_pm_ops mdp4_pm_ops = {
> >>> static int mdp4_probe(struct platform_device *pdev)
> >>> {
> >>> - return msm_drv_probe(&pdev->dev, mdp4_kms_init, NULL);
> >>> + struct device *dev = &pdev->dev;
> >>> + struct mdp4_kms *mdp4_kms;
> >>> + int irq;
> >>> +
> >>> + mdp4_kms = devm_kzalloc(dev, sizeof(*mdp4_kms), GFP_KERNEL);
> >>> + if (!mdp4_kms)
> >>> + return dev_err_probe(dev, -ENOMEM, "failed to allocate kms\n");
> >>> +
> >>> + mdp4_kms->mmio = msm_ioremap(pdev, NULL);
> >>> + if (IS_ERR(mdp4_kms->mmio))
> >>> + return PTR_ERR(mdp4_kms->mmio);
> >>> +
> >>> + irq = platform_get_irq(pdev, 0);
> >>> + if (irq < 0)
> >>> + return dev_err_probe(dev, irq, "failed to get irq\n");
> >>> +
> >>> + mdp4_kms->base.base.irq = irq;
> >>> +
> >>> + /* NOTE: driver for this regulator still missing upstream.. use
> >>> + * _get_exclusive() and ignore the error if it does not exist
> >>> + * (and hope that the bootloader left it on for us)
> >>> + */
> >>> + mdp4_kms->vdd = devm_regulator_get_exclusive(&pdev->dev, "vdd");
> >>> + if (IS_ERR(mdp4_kms->vdd))
> >>> + mdp4_kms->vdd = NULL;
> >>> +
> >>> + mdp4_kms->clk = devm_clk_get(&pdev->dev, "core_clk");
> >>> + if (IS_ERR(mdp4_kms->clk))
> >>> + return dev_err_probe(dev, PTR_ERR(mdp4_kms->clk), "failed to get core_clk\n");
> >>> +
> >>> + mdp4_kms->pclk = devm_clk_get(&pdev->dev, "iface_clk");
> >>> + if (IS_ERR(mdp4_kms->pclk))
> >>> + mdp4_kms->pclk = NULL;
> >>> +
> >>> + mdp4_kms->axi_clk = devm_clk_get(&pdev->dev, "bus_clk");
> >>> + if (IS_ERR(mdp4_kms->axi_clk))
> >>> + return dev_err_probe(dev, PTR_ERR(mdp4_kms->axi_clk), "failed to get axi_clk\n");
> >>> +
> >>> + /*
> >>> + * This is required for revn >= 2. Handle errors here and let the kms
> >>> + * init bail out if the clock is not provided.
> >>> + */
> >>> + mdp4_kms->lut_clk = devm_clk_get_optional(&pdev->dev, "lut_clk");
> >>> + if (IS_ERR(mdp4_kms->lut_clk))
> >>> + return dev_err_probe(dev, PTR_ERR(mdp4_kms->lut_clk), "failed to get lut_clk\n");
> >>
> >> I can see that you have moved this from init to probe and only rev >=2 needs it.
> >>
> >> But, your check here will end up returning from probe because you have a return. So I guess you means just having dev_err_probe without the return and let the init fail if the clk is not found because we have the hw_rev only in init.
> >
> > No. The function called here is the devm_clk_get_optional(). So the driver will get NULL if the clock is not present in the DT and an error only in an error case (e.g. EINVAL, EPROBE_DEFER).
> >
> > Later on the mdp4_kms_init() will check hw_rev and return -ENODEV if the clock is required, but is set to NULL (not present in DT).
> >
>
> Ok, I have understood. But dont you think this is too much convolution
> just for this check? Why not leave the lut_clk in the init instead of
> trying to move it to probe and add all this?
No, I don't. I saw no point in leaving the lut_clk getter unconverted.
Having everything handled in a similar way is a neat bonus from my
point of view.
--
With best wishes
Dmitry
