linux-kernel - Re: [PATCH v3 8/9] drm/tegra: vic: Implement get_streamid

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Message-ID: <71e94ac3-20fc-6f41-270f-fe246740e7e0@arm.com>
Date:   Mon, 21 Feb 2022 17:27:30 +0000
From:   Robin Murphy <robin.murphy@....com>
To:     Mikko Perttunen <mperttunen@...dia.com>, thierry.reding@...il.com,
        jonathanh@...dia.com, joro@...tes.org, will@...nel.org,
        robh+dt@...nel.org
Cc:     devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, iommu@...ts.linux-foundation.org,
        linux-tegra@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v3 8/9] drm/tegra: vic: Implement get_streamid_offset

On 2022-02-18 11:39, Mikko Perttunen via iommu wrote:
> Implement the get_streamid_offset required for supporting context
> isolation. Since old firmware cannot support context isolation
> without hacks that we don't want to implement, check the firmware
> binary to see if context isolation should be enabled.
> 
> Signed-off-by: Mikko Perttunen <mperttunen@...dia.com>
> ---
>   drivers/gpu/drm/tegra/vic.c | 38 +++++++++++++++++++++++++++++++++++++
>   1 file changed, 38 insertions(+)
> 
> diff --git a/drivers/gpu/drm/tegra/vic.c b/drivers/gpu/drm/tegra/vic.c
> index 1e342fa3d27b..2863ee5e0e67 100644
> --- a/drivers/gpu/drm/tegra/vic.c
> +++ b/drivers/gpu/drm/tegra/vic.c
> @@ -38,6 +38,8 @@ struct vic {
>   	struct clk *clk;
>   	struct reset_control *rst;
>   
> +	bool can_use_context;
> +
>   	/* Platform configuration */
>   	const struct vic_config *config;
>   };
> @@ -229,6 +231,7 @@ static int vic_load_firmware(struct vic *vic)
>   {
>   	struct host1x_client *client = &vic->client.base;
>   	struct tegra_drm *tegra = vic->client.drm;
> +	u32 fce_bin_data_offset;
>   	dma_addr_t iova;
>   	size_t size;
>   	void *virt;
> @@ -277,6 +280,25 @@ static int vic_load_firmware(struct vic *vic)
>   		vic->falcon.firmware.phys = phys;
>   	}
>   
> +	/*
> +	 * Check if firmware is new enough to not require mapping firmware
> +	 * to data buffer domains.
> +	 */
> +	fce_bin_data_offset = *(u32 *)(virt + VIC_UCODE_FCE_DATA_OFFSET);
> +
> +	if (!vic->config->supports_sid) {
> +		vic->can_use_context = false;
> +	} else if (fce_bin_data_offset != 0x0 && fce_bin_data_offset != 0xa5a5a5a5) {
> +		/*
> +		 * Firmware will access FCE through STREAMID0, so context
> +		 * isolation cannot be used.
> +		 */
> +		vic->can_use_context = false;
> +		dev_warn_once(vic->dev, "context isolation disabled due to old firmware\n");
> +	} else {
> +		vic->can_use_context = true;
> +	}
> +
>   	return 0;
>   
>   cleanup:
> @@ -358,10 +380,26 @@ static void vic_close_channel(struct tegra_drm_context *context)
>   	host1x_channel_put(context->channel);
>   }
>   
> +static int vic_get_streamid_offset(struct tegra_drm_client *client)
> +{
> +	struct vic *vic = to_vic(client);
> +	int err;
> +
> +	err = vic_load_firmware(vic);
> +	if (err < 0)
> +		return err;
> +
> +	if (vic->can_use_context)
> +		return 0x30;
> +	else
> +		return -ENOTSUPP;
> +}
> +
>   static const struct tegra_drm_client_ops vic_ops = {
>   	.open_channel = vic_open_channel,
>   	.close_channel = vic_close_channel,
>   	.submit = tegra_drm_submit,
> +	.get_streamid_offset = vic_get_streamid_offset,

The patch order seems off here, since the .get_streamid_offset member 
isn't defined yet.

Robin.

>   };
>   
>   #define NVIDIA_TEGRA_124_VIC_FIRMWARE "nvidia/tegra124/vic03_ucode.bin"