Hi Houlong,
Thank you for following up this patchset. I have some questions to try to
understand better the hardware though.
On 25/8/21 10:43, houlong wei wrote:
> Hi Eizan,
>
> Thanks for you patch. I have inline comment below.
>
> Regards,
> Houlong
>
> On Wed, 2021-08-25 at 14:33 +0800, 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>
>> Reviewed-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
>> ---
>>
>> (no changes since v1)
>>
>> drivers/media/platform/mtk-mdp/mtk_mdp_comp.c | 56 +++++++++++++------
>> drivers/media/platform/mtk-mdp/mtk_mdp_core.c | 36 ++++++++----
>> 2 files changed, 64 insertions(+), 28 deletions(-)
>>
>> diff --git a/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c b/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
>> index 85ef274841a3..9527649de98e 100644
>> --- a/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
>> +++ b/drivers/media/platform/mtk-mdp/mtk_mdp_comp.c
>> @@ -151,29 +151,50 @@ void mtk_mdp_comp_clock_off(struct mtk_mdp_comp *comp)
>> mtk_smi_larb_put(comp->larb_dev);
>> }
>>
>> -static int mtk_mdp_comp_bind(struct device *dev, struct device *master, void *data)
>> +/*
>> + * The MDP master device node is identified by the device tree alias
>> + * "mdp-rdma0".
>> + */
>> +static bool is_mdp_master(struct device *dev)
>> +{
>> + struct device_node *aliases, *mdp_rdma0_node;
>> + const char *mdp_rdma0_path;
>> +
>> + if (!dev->of_node)
>> + return false;
>> +
>> + aliases = of_find_node_by_path("/aliases");
>> + if (!aliases) {
>> + dev_err(dev, "no aliases found for mdp-rdma0");
>> + return false;
>> + }
>> +
>> + 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 false;
>> + }
>> +
>> + 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 false;
>> + }
>> +
>> + return dev->of_node == mdp_rdma0_node;
>
>
> About how to determine the master mdp driver, we also can
> judge the component type. The component type can be gotten by calling
> of_device_get_match_data(dev). If the component is MTK_MDP_RDMA, it is
> the master driver. No matter it is mdp_rdma0 or mdp_rdma1.
I'm confused, you mean that the component type, aka MTK_MDP_RDMA is only set for
mtk_mdp_rdma0? isn't mtk_dmp_rdma1 also a MTK_MDP_RDMA type? Because looks weird
to me that two rdma have diffent types.
> http://lists.infradead.org/pipermail/linux-mediatek/2021-August/028533.html
>
> IMO, judging it by component type is more flexible because it does not
> limit to 'mdp_rdma0'.
>
Using an alias like Eizan did is also flexible, you only need to set mdp-rdma0
to point the mdp_rdma1 node.
What I am really interested to know is the differences between the platforms to
understand if this is really a platform hardware property or a software
configurable thing, so would help if you can give use the different use cases
for different SoCs.
For MT8173 which is the master device? is _always_ rdma0 or can also be rdma1?
Or maybe what is not clear here is what exactly means be a master device?
What about MT8183 and other SoCs?
Thanks,
Enric
>> +}
>> +
>> +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;
>>
>> - mdp->vpu_dev = of_find_device_by_node(vpu_node);
>> - if (WARN_ON(!mdp->vpu_dev)) {
>> - dev_err(dev, "vpu pdev failed\n");
>> - of_node_put(vpu_node);
>> - }
>> -
>> ret = v4l2_device_register(dev, &mdp->v4l2_dev);
>> if (ret) {
>> dev_err(dev, "Failed to register v4l2 device\n");
>> @@ -187,9 +208,8 @@ static int mtk_mdp_comp_bind(struct device *dev, struct device *master, void *da
>> }
>>
>> /*
>> - * 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 50eafcc9993d..6a775463399c 100644
>> --- a/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
>> +++ b/drivers/media/platform/mtk-mdp/mtk_mdp_core.c
>> @@ -150,8 +150,9 @@ static void release_of(struct device *dev, void *data)
>>
>> static int mtk_mdp_master_bind(struct device *dev)
>> {
>> - int status;
>> struct mtk_mdp_dev *mdp = dev_get_drvdata(dev);
>> + struct device_node *vpu_node;
>> + int status;
>>
>> status = component_bind_all(dev, mdp);
>> if (status) {
>> @@ -159,15 +160,30 @@ static int mtk_mdp_master_bind(struct device *dev)
>> goto err_component_bind_all;
>> }
>>
>> - if (mdp->vpu_dev) {
>> - int ret = vpu_wdt_reg_handler(mdp->vpu_dev, mtk_mdp_reset_handler, mdp,
>> - VPU_RST_MDP);
>> - if (ret) {
>> - dev_err(dev, "Failed to register reset handler\n");
>> - goto err_wdt_reg;
>> - }
>> - } else {
>> - dev_err(dev, "no vpu_dev found\n");
>> + 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");
>> + status = -ENODEV;
>> + goto err_wdt_reg;
>> + }
>> +
>> + mdp->vpu_dev = of_find_device_by_node(vpu_node);
>
> The 'vpu_node' should be put by calling 'of_node_put(vpu_node)' when it
> is not used.
>
>> + if (!mdp->vpu_dev) {
>> + dev_err(dev, "unable to find vpu device");
>> + status = -ENODEV;
>> + goto err_wdt_reg;
>> + }
>> +
>> + status = vpu_wdt_reg_handler(mdp->vpu_dev, mtk_mdp_reset_handler, mdp, VPU_RST_MDP);
>> + if (status) {
>> + dev_err(dev, "Failed to register reset handler\n");
>> + goto err_wdt_reg;
>> }
>>
>> status = mtk_mdp_register_m2m_device(mdp);
>
