linux-kernel - Re: [PATCH 1/3] drm/msm: support firmware-name for zap fw

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Message-ID: <20200108184850.GA13260@jcrouse1-lnx.qualcomm.com>
Date:   Wed, 8 Jan 2020 11:48:50 -0700
From:   Jordan Crouse <jcrouse@...eaurora.org>
To:     Rob Clark <robdclark@...il.com>
Cc:     dri-devel@...ts.freedesktop.org, devicetree@...r.kernel.org,
        freedreno@...ts.freedesktop.org, linux-arm-msm@...r.kernel.org,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Sharat Masetty <smasetty@...eaurora.org>,
        Rob Clark <robdclark@...omium.org>,
        Sean Paul <sean@...rly.run>, David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Douglas Anderson <dianders@...omium.org>,
        Brian Masney <masneyb@...tation.org>,
        Fabio Estevam <festevam@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/3] drm/msm: support firmware-name for zap fw

On Tue, Jan 07, 2020 at 05:38:42PM -0800, Rob Clark wrote:
> From: Rob Clark <robdclark@...omium.org>
> 
> Since zap firmware can be device specific, allow for a firmware-name
> property in the zap node to specify which firmware to load, similarly to
> the scheme used for dsp/wifi/etc.
> 
> Signed-off-by: Rob Clark <robdclark@...omium.org>
> ---
>  drivers/gpu/drm/msm/adreno/adreno_gpu.c | 32 ++++++++++++++++++++++---
>  1 file changed, 29 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> index 112e8b8a261e..aa8737bd58db 100644
> --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c
> @@ -26,6 +26,7 @@ static int zap_shader_load_mdt(struct msm_gpu *gpu, const char *fwname,
>  {
>  	struct device *dev = &gpu->pdev->dev;
>  	const struct firmware *fw;
> +	const char *signed_fwname = NULL;
>  	struct device_node *np, *mem_np;
>  	struct resource r;
>  	phys_addr_t mem_phys;
> @@ -58,8 +59,33 @@ static int zap_shader_load_mdt(struct msm_gpu *gpu, const char *fwname,
>  
>  	mem_phys = r.start;
>  
> -	/* Request the MDT file for the firmware */
> -	fw = adreno_request_fw(to_adreno_gpu(gpu), fwname);
> +	/*
> +	 * Check for a firmware-name property.  This is the new scheme
> +	 * to handle firmware that may be signed with device specific
> +	 * keys, allowing us to have a different zap fw path for different
> +	 * devices.
> +	 *
> +	 * If the firmware-name property is found, we bypass the
> +	 * adreno_request_fw() mechanism, because we don't need to handle
> +	 * the /lib/firmware/qcom/* vs /lib/firmware/* case.
> +	 *
> +	 * If the firmware-name property is not found, for backwards
> +	 * compatibility we fall back to the fwname from the gpulist
> +	 * table.
> +	 */
> +	of_property_read_string_index(np, "firmware-name", 0, &signed_fwname);
> +	if (signed_fwname) {
> +		fwname = signed_fwname;
> +		ret = request_firmware_direct(&fw, signed_fwname, gpu->dev->dev);
> +		if (ret) {
> +			DRM_DEV_ERROR(dev, "could not load signed zap firmware: %d\n", ret);
> +			fw = ERR_PTR(ret);
> +		}
> +	} else {
> +		/* Request the MDT file for the firmware */
> +		fw = adreno_request_fw(to_adreno_gpu(gpu), fwname);
> +	}
> +

Since DT seems to be the trend for target specific firmware names I think we
should plan to quickly deprecate the legacy name and not require new targets to
set it. If a zap node is going to be opt in then it isn't onerous to ask
the developer to set the additional property for each target platform.

Jordan

>  	if (IS_ERR(fw)) {
>  		DRM_DEV_ERROR(dev, "Unable to load %s\n", fwname);
>  		return PTR_ERR(fw);
> @@ -95,7 +121,7 @@ static int zap_shader_load_mdt(struct msm_gpu *gpu, const char *fwname,
>  	 * not.  But since we've already gotten through adreno_request_fw()
>  	 * we know which of the two cases it is:
>  	 */
> -	if (to_adreno_gpu(gpu)->fwloc == FW_LOCATION_LEGACY) {
> +	if (signed_fwname || (to_adreno_gpu(gpu)->fwloc == FW_LOCATION_LEGACY)) {
>  		ret = qcom_mdt_load(dev, fw, fwname, pasid,
>  				mem_region, mem_phys, mem_size, NULL);
>  	} else {
> -- 
> 2.24.1
> 

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