Re: [PATCH v4 1/3] media: venus: Add support for static video encoder/decoder declarations

[Dikshita Agarwal <quic_dikshita@quicinc.com>]

On 11/28/2024 9:51 PM, Bryan O'Donoghue wrote:
> Add resource structure data and probe() logic to support static
> declarations of encoder and decoder.
> 
> Right now we rely on video encoder/decoder selection happening in the dtb
> but, this goes against the remit of device tree which is supposed to
> describe hardware, not select functional logic in Linux drivers.
> 
> Provide two strings in the venus resource structure enc_nodename and
> dec_nodename.
> 
> When set the venus driver will create an OF entry in-memory consistent
> with:
> 
> dec_nodename {
>     compat = "video-decoder";
> };
> 
> and/or
> 
> enc_nodename {
>     compat = "video-encoder";
> };
> 
> This will allow us to reuse the existing driver scheme of relying on compat
> names maintaining compatibility with old dtb files.
> 
> dec_nodename can be "video-decoder" or "video0"
> enc_nodename can be "video-encoder" or "video1"
> 
> This change relies on of_changeset() API as a result select OF_DYNAMIC will
> be added to venus/Kconfig
> 
> Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
> ---
>  drivers/media/platform/qcom/venus/Kconfig |  1 +
>  drivers/media/platform/qcom/venus/core.c  | 90 +++++++++++++++++++++++++++++++
>  drivers/media/platform/qcom/venus/core.h  |  4 ++
>  3 files changed, 95 insertions(+)
> 
> diff --git a/drivers/media/platform/qcom/venus/Kconfig b/drivers/media/platform/qcom/venus/Kconfig
> index bfd50e8f34219db8a1de7960d7ea93b20db2982a..bc2e410b29cb415a36540a4f98709eae44f4ec35 100644
> --- a/drivers/media/platform/qcom/venus/Kconfig
> +++ b/drivers/media/platform/qcom/venus/Kconfig
> @@ -3,6 +3,7 @@ config VIDEO_QCOM_VENUS
>  	depends on V4L_MEM2MEM_DRIVERS
>  	depends on VIDEO_DEV && QCOM_SMEM
>  	depends on (ARCH_QCOM && IOMMU_DMA) || COMPILE_TEST
> +	select OF_DYNAMIC if ARCH_QCOM
>  	select QCOM_MDT_LOADER if ARCH_QCOM
>  	select QCOM_SCM
>  	select VIDEOBUF2_DMA_CONTIG
> diff --git a/drivers/media/platform/qcom/venus/core.c b/drivers/media/platform/qcom/venus/core.c
> index 4e26b18790537885a77d66c1917a4e7a146eaf57..8a085611443cfda89ae71496e320dfc1f02ade88 100644
> --- a/drivers/media/platform/qcom/venus/core.c
> +++ b/drivers/media/platform/qcom/venus/core.c
> @@ -286,6 +286,89 @@ static irqreturn_t venus_isr_thread(int irq, void *dev_id)
>  	return ret;
>  }
>  
> +#if defined(CONFIG_OF_DYNAMIC)
> +static int venus_add_video_core(struct venus_core *core, const char *node_name,
> +				const char *compat)
> +{
> +	struct of_changeset *ocs = core->ocs;
> +	struct device *dev = core->dev;
> +	struct device_node *np, *enp;
> +	int ret;
> +
> +	if (!node_name)
> +		return 0;> +
> +	enp = of_find_node_by_name(dev->of_node, node_name);
> +	if (enp) {
> +		of_node_put(enp);
> +		return 0;
> +	}
> +
> +	np = of_changeset_create_node(ocs, dev->of_node, node_name);
> +	if (!np) {
> +		dev_err(dev, "Unable to create new node\n");
> +		return -ENODEV;
> +	}
> +
> +	ret = of_changeset_add_prop_string(ocs, np, "compatible", compat);
> +	if (ret)
> +		dev_err(dev, "unable to add %s\n", compat);
> +
> +	of_node_put(np);
> +
> +	return ret;
> +}
> +
> +static int venus_add_dynamic_nodes(struct venus_core *core)
> +{
> +	struct device *dev = core->dev;
> +	int ret;
> +
> +	core->ocs = kmalloc(sizeof(*core->ocs), GFP_KERNEL);
> +	if (!core->ocs)
> +		return -ENOMEM;
> +
> +	of_changeset_init(core->ocs);
> +
> +	ret = venus_add_video_core(core, core->res->dec_nodename, "venus-decoder");
> +	if (ret)
> +		goto err;
> +
> +	ret = venus_add_video_core(core, core->res->enc_nodename, "venus-encoder");
> +	if (ret)
> +		goto err;
> +
> +	ret = of_changeset_apply(core->ocs);
> +	if (ret) {
> +		dev_err(dev, "applying changeset fail ret %d\n", ret);
> +		goto err;
> +	}
> +
> +	return 0;
> +err:
> +	of_changeset_destroy(core->ocs);
> +	kfree(core->ocs);
> +	core->ocs = NULL;
> +	return ret;
> +}
> +
> +static void venus_remove_dynamic_nodes(struct venus_core *core)
> +{
> +	if (core->ocs) {
> +		of_changeset_revert(core->ocs);
> +		of_changeset_destroy(core->ocs);
> +		kfree(core->ocs);
> +	}
> +}
> +#else
> +static int venus_add_dynamic_nodes(struct venus_core *core)
> +{
> +	return 0;
> +}
> +
> +static void venus_remove_dynamic_nodes(struct venus_core *core) {}
> +#endif
> +
>  static int venus_probe(struct platform_device *pdev)
>  {
>  	struct device *dev = &pdev->dev;
> @@ -365,6 +448,11 @@ static int venus_probe(struct platform_device *pdev)
>  	if (ret < 0)
>  		goto err_runtime_disable;
>  
> +	if (core->res->dec_nodename || core->res->enc_nodename) {
> +		if (venus_add_dynamic_nodes(core))
> +			goto err_runtime_disable;
> +	}
> +
>  	ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
>  	if (ret)
>  		goto err_runtime_disable;
venus_remove_dynamic_nodes should be called in error handling in probe as
well I think.

Thanks,
Dikshita
> @@ -443,6 +531,8 @@ static void venus_remove(struct platform_device *pdev)
>  
>  	venus_firmware_deinit(core);
>  
> +	venus_remove_dynamic_nodes(core);
> +
>  	pm_runtime_put_sync(dev);
>  	pm_runtime_disable(dev);
>  
> diff --git a/drivers/media/platform/qcom/venus/core.h b/drivers/media/platform/qcom/venus/core.h
> index 27784fd7082c321222b23ca4b2902a04c49e19ca..306231b4f7d0201175974b4a42574f30d23e08f0 100644
> --- a/drivers/media/platform/qcom/venus/core.h
> +++ b/drivers/media/platform/qcom/venus/core.h
> @@ -90,6 +90,8 @@ struct venus_resources {
>  	u32 cp_nonpixel_start;
>  	u32 cp_nonpixel_size;
>  	const char *fwname;
> +	const char *enc_nodename;
> +	const char *dec_nodename;
>  };
>  
>  enum venus_fmt {
> @@ -171,6 +173,7 @@ struct venus_format {
>   * @root:	debugfs root directory
>   * @venus_ver:	the venus firmware version
>   * @dump_core:	a flag indicating that a core dump is required
> + * @ocs:	OF changeset pointer
>   */
>  struct venus_core {
>  	void __iomem *base;
> @@ -235,6 +238,7 @@ struct venus_core {
>  		u32 rev;
>  	} venus_ver;
>  	unsigned long dump_core;
> +	struct of_changeset *ocs;
>  };
>  
>  struct vdec_controls {
>