linux-kernel - Re: [PATCH] media: venus: firmware: Use of_reserved_mem

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Message-ID: <384226b0-c952-95ac-fa77-8461b231dbbd@quicinc.com>
Date:   Wed, 31 May 2023 14:25:12 +0530
From:   Vikash Garodia <quic_vgarodia@...cinc.com>
To:     Stephan Gerhold <stephan@...hold.net>,
        Stanimir Varbanov <stanimir.k.varbanov@...il.com>
CC:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        <linux-media@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] media: venus: firmware: Use of_reserved_mem_lookup()


On 5/29/2023 11:46 PM, Stephan Gerhold wrote:
> Reserved memory can be either looked up using the generic function
> of_address_to_resource() or using the special of_reserved_mem_lookup().
> The latter has the advantage that it ensures that the referenced memory
> region was really reserved and is not e.g. status = "disabled".
> 
> of_reserved_mem also supports allocating reserved memory dynamically at
> boot time. This works only when using of_reserved_mem_lookup() since
> there won't be a fixed address in the device tree.
> 
> Switch the code to use of_reserved_mem_lookup(). There is no functional
> difference for static reserved memory allocations.
> 
> Signed-off-by: Stephan Gerhold <stephan@...hold.net>

Reviewed-by: Vikash Garodia <quic_vgarodia@...cinc.com>

> ---
> See e.g. [1] for an example of dynamically allocated reserved memory.
> (This patch does *not* depend on [1] and is useful without as well...)
> 
> [1]: https://lore.kernel.org/linux-arm-msm/20230510-dt-resv-bottom-up-v1-5-3bf68873dbed@gerhold.net/
> ---
>  drivers/media/platform/qcom/venus/firmware.c | 24 +++++++++++++-----------
>  1 file changed, 13 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/media/platform/qcom/venus/firmware.c b/drivers/media/platform/qcom/venus/firmware.c
> index cfb11c551167..2e7ffdaff7b2 100644
> --- a/drivers/media/platform/qcom/venus/firmware.c
> +++ b/drivers/media/platform/qcom/venus/firmware.c
> @@ -10,6 +10,7 @@
>  #include <linux/io.h>
>  #include <linux/of.h>
>  #include <linux/of_address.h>
> +#include <linux/of_reserved_mem.h>
>  #include <linux/platform_device.h>
>  #include <linux/of_device.h>
>  #include <linux/firmware/qcom/qcom_scm.h>
> @@ -82,9 +83,9 @@ static int venus_load_fw(struct venus_core *core, const char *fwname,
>  			 phys_addr_t *mem_phys, size_t *mem_size)
>  {
>  	const struct firmware *mdt;
> +	struct reserved_mem *rmem;
>  	struct device_node *node;
>  	struct device *dev;
> -	struct resource r;
>  	ssize_t fw_size;
>  	void *mem_va;
>  	int ret;
> @@ -99,13 +100,16 @@ static int venus_load_fw(struct venus_core *core, const char *fwname,
>  		return -EINVAL;
>  	}
>  
> -	ret = of_address_to_resource(node, 0, &r);
> -	if (ret)
> -		goto err_put_node;
> +	rmem = of_reserved_mem_lookup(node);
> +	of_node_put(node);
> +	if (!rmem) {
> +		dev_err(dev, "failed to lookup reserved memory-region\n");
> +		return -EINVAL;
> +	}
>  
>  	ret = request_firmware(&mdt, fwname, dev);
>  	if (ret < 0)
> -		goto err_put_node;
> +		return ret;
>  
>  	fw_size = qcom_mdt_get_size(mdt);
>  	if (fw_size < 0) {
> @@ -113,17 +117,17 @@ static int venus_load_fw(struct venus_core *core, const char *fwname,
>  		goto err_release_fw;
>  	}
>  
> -	*mem_phys = r.start;
> -	*mem_size = resource_size(&r);
> +	*mem_phys = rmem->base;
> +	*mem_size = rmem->size;
>  
>  	if (*mem_size < fw_size || fw_size > VENUS_FW_MEM_SIZE) {
>  		ret = -EINVAL;
>  		goto err_release_fw;
>  	}
>  
> -	mem_va = memremap(r.start, *mem_size, MEMREMAP_WC);
> +	mem_va = memremap(*mem_phys, *mem_size, MEMREMAP_WC);
>  	if (!mem_va) {
> -		dev_err(dev, "unable to map memory region: %pR\n", &r);
> +		dev_err(dev, "unable to map memory region %pa size %#zx\n", mem_phys, *mem_size);
>  		ret = -ENOMEM;
>  		goto err_release_fw;
>  	}
> @@ -138,8 +142,6 @@ static int venus_load_fw(struct venus_core *core, const char *fwname,
>  	memunmap(mem_va);
>  err_release_fw:
>  	release_firmware(mdt);
> -err_put_node:
> -	of_node_put(node);
>  	return ret;
>  }
>  
> 
> ---
> base-commit: 9f9f8ca6f012d25428f8605cb36369a449db8508
> change-id: 20230529-venus-of-rmem-f649885114fd
> 
> Best regards,