Hi Eizan,
Thank you for your patch.
On 9/7/21 4:23, Eizan Miyamoto wrote:
> ... Instead of depending on the presence of a mediatek,vpu property in
> the device node.
>
> That property was originally added to link to the vpu node so that the
> mtk_mdp_core driver could pass the right device to
> vpu_wdt_reg_handler(). However in a previous patch in this series,
> the driver has been modified to search the device tree for that node
> instead.
>
> That property was also used to indicate the primary MDP device, so that
> it can be passed to the V4L2 subsystem as well as register it to be
> used when setting up queues in the open() callback for the filesystem
> device node that is created. In this case, assuming that the primary
> MDP device is the one with a specific alias seems useable because the
> alternative is to add a property to the device tree which doesn't
> actually represent any facet of hardware (i.e., this being the primary
> MDP device is a software decision). In other words, this solution is
> equally as arbitrary, but at least it doesn't add a property to a
> device node where said property is unrelated to the hardware present.
>
> Signed-off-by: Eizan Miyamoto <eizan@xxxxxxxxxxxx>
> ---
>
> (no changes since v1)
>
> drivers/media/platform/mtk-mdp/mtk_mdp_comp.c | 47 ++++++++++++++-----
> drivers/media/platform/mtk-mdp/mtk_mdp_core.c | 6 +++
> 2 files changed, 42 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c b/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
> index 87e3f72ff02b..de2d425efdd1 100644
> --- a/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
> +++ b/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
> @@ -151,22 +151,48 @@ void mtk_mdp_comp_clock_off(struct mtk_mdp_comp *comp)
> mtk_smi_larb_put(comp->larb_dev);
> }
>
> +/*
> + * The MDP master device node is identified by the device tree alias
> + * "mdp-rdma0".
> + */
> +static int is_mdp_master(struct device *dev)
bool ? (and return true/false)
> +{
> + struct device_node *aliases, *mdp_rdma0_node;
> + const char *mdp_rdma0_path;
> +
> + if (!dev->of_node)
> + return 0;
> +
> + aliases = of_find_node_by_path("/aliases");
> + if (!aliases) {
> + dev_err(dev, "no aliases found for mdp-rdma0");
> + return 0;
> + }
> +
> + mdp_rdma0_path = of_get_property(aliases, "mdp-rdma0", NULL);
> + if (!mdp_rdma0_path) {
> + dev_err(dev, "get mdp-rdma0 property of /aliases failed");
> + return 0;
> + }
> +
> + mdp_rdma0_node = of_find_node_by_path(mdp_rdma0_path);
> + if (!mdp_rdma0_node) {
> + dev_err(dev, "path resolution failed for %s", mdp_rdma0_path);
> + return 0;
> + }
> +
> + return dev->of_node == mdp_rdma0_node;
> +}
> +
> static int mtk_mdp_comp_bind(struct device *dev, struct device *master,
> void *data)
> {
> struct mtk_mdp_comp *comp = dev_get_drvdata(dev);
> struct mtk_mdp_dev *mdp = data;
> - struct device_node *vpu_node;
>
> mtk_mdp_register_component(mdp, comp);
>
> - /*
> - * If this component has a "mediatek-vpu" property, it is responsible for
> - * notifying the mdp master driver about it so it can be further initialized
> - * later.
> - */
> - vpu_node = of_parse_phandle(dev->of_node, "mediatek,vpu", 0);
> - if (vpu_node) {
> + if (is_mdp_master(dev)) {
> int ret;
>
> ret = v4l2_device_register(dev, &mdp->v4l2_dev);
> @@ -182,9 +208,8 @@ static int mtk_mdp_comp_bind(struct device *dev, struct device *master,
> }
>
> /*
> - * presence of the "mediatek,vpu" property in a device node
> - * indicates that it is the primary MDP rdma device and MDP DMA
> - * ops should be handled by its DMA callbacks.
> + * MDP DMA ops will be handled by the DMA callbacks associated with this
> + * device;
> */
> mdp->rdma_dev = dev;
> }
> diff --git a/drivers/media/platform/mtk-mdp/mtk_mdp_core.c b/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
> index b45d588d2659..e1fb39231248 100644
> --- a/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
> +++ b/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
> @@ -158,6 +158,12 @@ static int mtk_mdp_master_bind(struct device *dev)
> goto err_component_bind_all;
> }
>
> + if (mdp->rdma_dev == NULL) {
> + dev_err(dev, "Primary MDP device not found");
> + status = -ENODEV;
> + goto err_component_bind_all;
> + }
> +
> vpu_node = of_find_node_by_name(NULL, "vpu");
> if (!vpu_node) {
> dev_err(dev, "unable to find vpu node");
>
