Re: [PATCH] drm/msm: Set max segment size earlier

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 01/05/2023 23:44, Rob Clark wrote:
> From: Rob Clark <robdclark@chromium.org>
> 
> Fixes the following splat on a6xx gen2+ (a640, a650, a660 families),
> a6xx gen1 has smaller GMU allocations so they fit under the default
> 64K max segment size.
> 
>     ------------[ cut here ]------------
>     DMA-API: msm_dpu ae01000.display-controller: mapping sg segment longer than device claims to support [len=126976] [max=65536]
>     WARNING: CPU: 5 PID: 9 at kernel/dma/debug.c:1160 debug_dma_map_sg+0x288/0x314
>     Modules linked in:
>     CPU: 5 PID: 9 Comm: kworker/u16:0 Not tainted 6.3.0-rc2-debug+ #629
>     Hardware name: Google Villager (rev1+) with LTE (DT)
>     Workqueue: events_unbound deferred_probe_work_func
>     pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>     pc : debug_dma_map_sg+0x288/0x314
>     lr : debug_dma_map_sg+0x288/0x314
>     sp : ffffffc00809b560
>     x29: ffffffc00809b560 x28: 0000000000000060 x27: 0000000000000000
>     x26: 0000000000010000 x25: 0000000000000004 x24: 0000000000000004
>     x23: ffffffffffffffff x22: ffffffdb31693cc0 x21: ffffff8080935800
>     x20: ffffff8087417400 x19: ffffff8087a45010 x18: 0000000000000000
>     x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000010000
>     x14: 0000000000000001 x13: ffffffffffffffff x12: ffffffffffffffff
>     x11: 0000000000000000 x10: 000000000000000a x9 : ffffffdb2ff05e14
>     x8 : ffffffdb31275000 x7 : ffffffdb2ff08908 x6 : 0000000000000000
>     x5 : 0000000000000001 x4 : ffffffdb2ff08a74 x3 : ffffffdb31275008
>     x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffffff80803a9a80
>     Call trace:
>      debug_dma_map_sg+0x288/0x314
>      __dma_map_sg_attrs+0x80/0xe4
>      dma_map_sgtable+0x30/0x4c
>      get_pages+0x1d4/0x1e4
>      msm_gem_pin_pages_locked+0xbc/0xf8
>      msm_gem_pin_vma_locked+0x58/0xa0
>      msm_gem_get_and_pin_iova_range+0x98/0xac
>      a6xx_gmu_memory_alloc+0x7c/0x128
>      a6xx_gmu_init+0x16c/0x9b0
>      a6xx_gpu_init+0x38c/0x3e4
>      adreno_bind+0x214/0x264
>      component_bind_all+0x128/0x1f8
>      msm_drm_bind+0x2b8/0x608
>      try_to_bring_up_aggregate_device+0x88/0x1a4
>      __component_add+0xec/0x13c
>      component_add+0x1c/0x28
>      dp_display_probe+0x3f8/0x43c
>      platform_probe+0x70/0xc4
>      really_probe+0x148/0x280
>      __driver_probe_device+0xc8/0xe0
>      driver_probe_device+0x44/0x100
>      __device_attach_driver+0x64/0xdc
>      bus_for_each_drv+0xb0/0xd8
>      __device_attach+0xd8/0x168
>      device_initial_probe+0x1c/0x28
>      bus_probe_device+0x44/0xb0
>      deferred_probe_work_func+0xc8/0xe0
>      process_one_work+0x2e0/0x488
>      process_scheduled_works+0x4c/0x50
>      worker_thread+0x218/0x274
>      kthread+0xf0/0x100
>      ret_from_fork+0x10/0x20
>     irq event stamp: 293712
>     hardirqs last  enabled at (293711): [<ffffffdb2ff0893c>] vprintk_emit+0x160/0x25c
>     hardirqs last disabled at (293712): [<ffffffdb30b48130>] el1_dbg+0x24/0x80
>     softirqs last  enabled at (279520): [<ffffffdb2fe10420>] __do_softirq+0x21c/0x4bc
>     softirqs last disabled at (279515): [<ffffffdb2fe16708>] ____do_softirq+0x18/0x24
>     ---[ end trace 0000000000000000 ]---
> 
> Signed-off-by: Rob Clark <robdclark@chromium.org>

I think this should be:

Fixes: db735fc4036b ("drm/msm: Set dma maximum segment size for mdss")

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

> ---
>   drivers/gpu/drm/msm/msm_drv.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/msm/msm_drv.c b/drivers/gpu/drm/msm/msm_drv.c
> index 3a74b5653e96..6dec1a3534f2 100644
> --- a/drivers/gpu/drm/msm/msm_drv.c
> +++ b/drivers/gpu/drm/msm/msm_drv.c
> @@ -440,27 +440,27 @@ static int msm_drm_init(struct device *dev, const struct drm_driver *drv)
>   	fs_reclaim_acquire(GFP_KERNEL);
>   	might_lock(&priv->lru.lock);
>   	fs_reclaim_release(GFP_KERNEL);
>   
>   	drm_mode_config_init(ddev);
>   
>   	ret = msm_init_vram(ddev);
>   	if (ret)
>   		goto err_drm_dev_put;
>   
> +	dma_set_max_seg_size(dev, UINT_MAX);
> +
>   	/* Bind all our sub-components: */
>   	ret = component_bind_all(dev, ddev);
>   	if (ret)
>   		goto err_drm_dev_put;
>   
> -	dma_set_max_seg_size(dev, UINT_MAX);
> -
>   	msm_gem_shrinker_init(ddev);
>   
>   	if (priv->kms_init) {
>   		ret = priv->kms_init(ddev);
>   		if (ret) {
>   			DRM_DEV_ERROR(dev, "failed to load kms\n");
>   			priv->kms = NULL;
>   			goto err_msm_uninit;
>   		}
>   		kms = priv->kms;

-- 
With best wishes
Dmitry