[PATCH] drm/amd/amdgpu: Add write() method to VRAM debugfs entry

[Christian König]

Am 29.08.2017 um 14:43 schrieb Tom St Denis:
> Allows writing data to vram via debugfs.
>
> Signed-off-by: Tom St Denis <tom.stdenis at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 41 ++++++++++++++++++++++++++++++++-
>   1 file changed, 40 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> index c97a99427eea..cdc96d027707 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> @@ -1671,10 +1671,49 @@ static ssize_t amdgpu_ttm_vram_read(struct file *f, char __user *buf,
>   	return result;
>   }
>   
> +static ssize_t amdgpu_ttm_vram_write(struct file *f, const char __user *buf,
> +				    size_t size, loff_t *pos)
> +{
> +	struct amdgpu_device *adev = file_inode(f)->i_private;
> +	ssize_t result = 0;
> +	int r;
> +
> +	if (size & 0x3 || *pos & 0x3)
> +		return -EINVAL;
> +
> +	if (*pos >= adev->mc.mc_vram_size)
> +		return -ENXIO;
> +
> +	while (size) {
> +		unsigned long flags;
> +		uint32_t value;
> +
> +		if (*pos >= adev->mc.mc_vram_size)
> +			return result;
> +
> +		spin_lock_irqsave(&adev->mmio_idx_lock, flags);
> +		WREG32(mmMM_INDEX, ((uint32_t)*pos) | 0x80000000);
> +		WREG32(mmMM_INDEX_HI, *pos >> 31);
> +		r = get_user(value, (uint32_t *)buf);

Don't call get_user() while holding a spin.

> +		if (r)
> +			return r;

You forget to unlock the spin.

Regards,
Christian.

> +		WREG32(mmMM_DATA, value);
> +		spin_unlock_irqrestore(&adev->mmio_idx_lock, flags);
> +
> +		result += 4;
> +		buf += 4;
> +		*pos += 4;
> +		size -= 4;
> +	}
> +
> +	return result;
> +}
> +
>   static const struct file_operations amdgpu_ttm_vram_fops = {
>   	.owner = THIS_MODULE,
>   	.read = amdgpu_ttm_vram_read,
> -	.llseek = default_llseek
> +	.write = amdgpu_ttm_vram_write,
> +	.llseek = default_llseek,
>   };
>   
>   #ifdef CONFIG_DRM_AMDGPU_GART_DEBUGFS