Commit d59e75ee authored by Danilo Krummrich's avatar Danilo Krummrich
Browse files

drm/nouveau: exec: report max pushs through getparam 



Report the maximum number of IBs that can be pushed with a single
DRM_IOCTL_NOUVEAU_EXEC through DRM_IOCTL_NOUVEAU_GETPARAM.

While the maximum number of IBs per ring might vary between chipsets,
the kernel will make sure that userspace can only push a fraction of the
maximum number of IBs per ring per job, such that we avoid a situation
where there's only a single job occupying the ring, which could
potentially lead to the ring run dry.

Using DRM_IOCTL_NOUVEAU_GETPARAM to report the maximum number of IBs
that can be pushed with a single DRM_IOCTL_NOUVEAU_EXEC implies that
all channels of a given device have the same ring size.

Reviewed-by: default avatarDave Airlie <airlied@redhat.com>
Reviewed-by: default avatarLyude Paul <lyude@redhat.com>
Acked-by: default avatarFaith Ekstrand <faith.ekstrand@collabora.com>
Signed-off-by: default avatarDanilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231002135008.10651-3-dakr@redhat.com
parent bbe08a0e

drivers/gpu/drm/nouveau/nouveau_abi16.c

+21 −0
Original line number Diff line number Diff line
@@ -31,6 +31,7 @@ 


#include "nouveau_drv.h"

#include "nouveau_dma.h"

#include "nouveau_exec.h"

#include "nouveau_gem.h"

#include "nouveau_chan.h"

#include "nouveau_abi16.h"
@@ -183,6 +184,20 @@ nouveau_abi16_fini(struct nouveau_abi16 *abi16) 
	cli->abi16 = NULL;

}



static inline int

getparam_dma_ib_max(struct nvif_device *device)

{

	const struct nvif_mclass dmas[] = {

		{ NV03_CHANNEL_DMA, 0 },

		{ NV10_CHANNEL_DMA, 0 },

		{ NV17_CHANNEL_DMA, 0 },

		{ NV40_CHANNEL_DMA, 0 },

		{}

	};



	return nvif_mclass(&device->object, dmas) < 0 ? NV50_DMA_IB_MAX : 0;

}



int

nouveau_abi16_ioctl_getparam(ABI16_IOCTL_ARGS)

{
@@ -247,6 +262,12 @@ nouveau_abi16_ioctl_getparam(ABI16_IOCTL_ARGS) 
	case NOUVEAU_GETPARAM_GRAPH_UNITS:

		getparam->value = nvkm_gr_units(gr);

		break;

	case NOUVEAU_GETPARAM_EXEC_PUSH_MAX: {

		int ib_max = getparam_dma_ib_max(device);



		getparam->value = nouveau_exec_push_max_from_ib_max(ib_max);

		break;

	}

	default:

		NV_PRINTK(dbg, cli, "unknown parameter %lld\n", getparam->param);

		return -EINVAL;

drivers/gpu/drm/nouveau/nouveau_chan.c

+1 −1
Original line number Diff line number Diff line
@@ -454,7 +454,7 @@ nouveau_channel_init(struct nouveau_channel *chan, u32 vram, u32 gart) 
		chan->user_get = 0x44;

		chan->user_get_hi = 0x60;

		chan->dma.ib_base =  0x10000 / 4;

		chan->dma.ib_max  = (0x02000 / 8) - 1;

		chan->dma.ib_max  = NV50_DMA_IB_MAX;

		chan->dma.ib_put  = 0;

		chan->dma.ib_free = chan->dma.ib_max - chan->dma.ib_put;

		chan->dma.max = chan->dma.ib_base;

drivers/gpu/drm/nouveau/nouveau_dma.h

+3 −0
Original line number Diff line number Diff line
@@ -49,6 +49,9 @@ void nv50_dma_push(struct nouveau_channel *, u64 addr, u32 length, 
/* Maximum push buffer size. */

#define NV50_DMA_PUSH_MAX_LENGTH 0x7fffff



/* Maximum IBs per ring. */

#define NV50_DMA_IB_MAX ((0x02000 / 8) - 1)



/* Object handles - for stuff that's doesn't use handle == oclass. */

enum {

	NvDmaFB		= 0x80000002,

drivers/gpu/drm/nouveau/nouveau_exec.c

+4 −3
Original line number Diff line number Diff line
@@ -379,7 +379,7 @@ nouveau_exec_ioctl_exec(struct drm_device *dev, 
	struct nouveau_channel *chan = NULL;

	struct nouveau_exec_job_args args = {};

	struct drm_nouveau_exec *req = data;

	int ret = 0;

	int push_max, ret = 0;



	if (unlikely(!abi16))

		return -ENOMEM;
@@ -404,9 +404,10 @@ nouveau_exec_ioctl_exec(struct drm_device *dev, 
	if (!chan->dma.ib_max)

		return nouveau_abi16_put(abi16, -ENOSYS);



	if (unlikely(req->push_count > NOUVEAU_GEM_MAX_PUSH)) {

	push_max = nouveau_exec_push_max_from_ib_max(chan->dma.ib_max);

	if (unlikely(req->push_count > push_max)) {

		NV_PRINTK(err, cli, "pushbuf push count exceeds limit: %d max %d\n",

			 req->push_count, NOUVEAU_GEM_MAX_PUSH);

			  req->push_count, push_max);

		return nouveau_abi16_put(abi16, -EINVAL);

	}

drivers/gpu/drm/nouveau/nouveau_exec.h

+10 −0
Original line number Diff line number Diff line
@@ -51,4 +51,14 @@ int nouveau_exec_job_init(struct nouveau_exec_job **job, 
int nouveau_exec_ioctl_exec(struct drm_device *dev, void *data,

			    struct drm_file *file_priv);



static inline unsigned int

nouveau_exec_push_max_from_ib_max(int ib_max)

{

	/* Limit the number of IBs per job to half the size of the ring in order

	 * to avoid the ring running dry between submissions and preserve one

	 * more slot for the job's HW fence.

	 */

	return ib_max > 1 ? ib_max / 2 - 1 : 0;

}



#endif