by Oleksandr Andrushchenko

[permalink] [raw]

Subject: Re: [PATCH 9/9] drm/xen-front: Implement communication with backend

On 03/06/2018 11:26 AM, Daniel Vetter wrote:
> On Mon, Mar 05, 2018 at 11:30:35AM +0200, Oleksandr Andrushchenko wrote:
>> On 03/05/2018 11:25 AM, Daniel Vetter wrote:
>>> On Wed, Feb 21, 2018 at 10:03:42AM +0200, Oleksandr Andrushchenko wrote:
>>>> From: Oleksandr Andrushchenko <[email protected]>
>>>>
>>>> Handle communication with the backend:
>>>> - send requests and wait for the responses according
>>>> to the displif protocol
>>>> - serialize access to the communication channel
>>>> - time-out used for backend communication is set to 3000 ms
>>>> - manage display buffers shared with the backend
>>>>
>>>> Signed-off-by: Oleksandr Andrushchenko <[email protected]>
>>> After the demidlayering it probably makes sense to merge this with the
>>> overall kms/basic-drm-driver patch. Up to you really.
>> The reason for such partitioning here and before was that
>> I can have Xen/DRM parts separate, so those are easier for
>> review by Xen/DRM communities. So, I would prefer to have it
>> as it is
> Well for reviewing the kms parts I need to check what the xen parts are
> doing (at least sometimes), since semantics of what you're doing matter,
> and there's a few cases which new drivers tend to get wrong. So for me,
> this splitting makes stuff actually harder to review.
>
> And I guess for the xen folks it won't hurt if they see a bit clearer how
> it's used on the drm side (even if they might not really understand what's
> going on). If we have some superficial abstraction in between each of the
> subsystem maintainers might make assumptions about what the other side of
> the code is doing which turn out to be wrong, and that's not good.
>
> Just explaining my motivation for why I don't like abstractions and
> splitting stuff up into patches that don't make much sense on their own
> (because the code is just hanging out there without being wired up
> anywhere).
Ok, no problem here. Will squash relevant patches then
> -Daniel
>>> -Daniel
>>>> ---
>>>> drivers/gpu/drm/xen/xen_drm_front.c | 327 +++++++++++++++++++++++++++++++++++-
>>>> drivers/gpu/drm/xen/xen_drm_front.h | 5 +
>>>> 2 files changed, 327 insertions(+), 5 deletions(-)
>>>>
>>>> diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c
>>>> index 8de88e359d5e..5ad546231d30 100644
>>>> --- a/drivers/gpu/drm/xen/xen_drm_front.c
>>>> +++ b/drivers/gpu/drm/xen/xen_drm_front.c
>>>> @@ -31,12 +31,146 @@
>>>> #include "xen_drm_front_evtchnl.h"
>>>> #include "xen_drm_front_shbuf.h"
>>>> +/* timeout in ms to wait for backend to respond */
>>>> +#define VDRM_WAIT_BACK_MS 3000
>>>> +
>>>> +struct xen_drm_front_dbuf {
>>>> + struct list_head list;
>>>> + uint64_t dbuf_cookie;
>>>> + uint64_t fb_cookie;
>>>> + struct xen_drm_front_shbuf *shbuf;
>>>> +};
>>>> +
>>>> +static int dbuf_add_to_list(struct xen_drm_front_info *front_info,
>>>> + struct xen_drm_front_shbuf *shbuf, uint64_t dbuf_cookie)
>>>> +{
>>>> + struct xen_drm_front_dbuf *dbuf;
>>>> +
>>>> + dbuf = kzalloc(sizeof(*dbuf), GFP_KERNEL);
>>>> + if (!dbuf)
>>>> + return -ENOMEM;
>>>> +
>>>> + dbuf->dbuf_cookie = dbuf_cookie;
>>>> + dbuf->shbuf = shbuf;
>>>> + list_add(&dbuf->list, &front_info->dbuf_list);
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static struct xen_drm_front_dbuf *dbuf_get(struct list_head *dbuf_list,
>>>> + uint64_t dbuf_cookie)
>>>> +{
>>>> + struct xen_drm_front_dbuf *buf, *q;
>>>> +
>>>> + list_for_each_entry_safe(buf, q, dbuf_list, list)
>>>> + if (buf->dbuf_cookie == dbuf_cookie)
>>>> + return buf;
>>>> +
>>>> + return NULL;
>>>> +}
>>>> +
>>>> +static void dbuf_flush_fb(struct list_head *dbuf_list, uint64_t fb_cookie)
>>>> +{
>>>> + struct xen_drm_front_dbuf *buf, *q;
>>>> +
>>>> + list_for_each_entry_safe(buf, q, dbuf_list, list)
>>>> + if (buf->fb_cookie == fb_cookie)
>>>> + xen_drm_front_shbuf_flush(buf->shbuf);
>>>> +}
>>>> +
>>>> +static void dbuf_free(struct list_head *dbuf_list, uint64_t dbuf_cookie)
>>>> +{
>>>> + struct xen_drm_front_dbuf *buf, *q;
>>>> +
>>>> + list_for_each_entry_safe(buf, q, dbuf_list, list)
>>>> + if (buf->dbuf_cookie == dbuf_cookie) {
>>>> + list_del(&buf->list);
>>>> + xen_drm_front_shbuf_unmap(buf->shbuf);
>>>> + xen_drm_front_shbuf_free(buf->shbuf);
>>>> + kfree(buf);
>>>> + break;
>>>> + }
>>>> +}
>>>> +
>>>> +static void dbuf_free_all(struct list_head *dbuf_list)
>>>> +{
>>>> + struct xen_drm_front_dbuf *buf, *q;
>>>> +
>>>> + list_for_each_entry_safe(buf, q, dbuf_list, list) {
>>>> + list_del(&buf->list);
>>>> + xen_drm_front_shbuf_unmap(buf->shbuf);
>>>> + xen_drm_front_shbuf_free(buf->shbuf);
>>>> + kfree(buf);
>>>> + }
>>>> +}
>>>> +
>>>> +static struct xendispl_req *be_prepare_req(
>>>> + struct xen_drm_front_evtchnl *evtchnl, uint8_t operation)
>>>> +{
>>>> + struct xendispl_req *req;
>>>> +
>>>> + req = RING_GET_REQUEST(&evtchnl->u.req.ring,
>>>> + evtchnl->u.req.ring.req_prod_pvt);
>>>> + req->operation = operation;
>>>> + req->id = evtchnl->evt_next_id++;
>>>> + evtchnl->evt_id = req->id;
>>>> + return req;
>>>> +}
>>>> +
>>>> +static int be_stream_do_io(struct xen_drm_front_evtchnl *evtchnl,
>>>> + struct xendispl_req *req)
>>>> +{
>>>> + reinit_completion(&evtchnl->u.req.completion);
>>>> + if (unlikely(evtchnl->state != EVTCHNL_STATE_CONNECTED))
>>>> + return -EIO;
>>>> +
>>>> + xen_drm_front_evtchnl_flush(evtchnl);
>>>> + return 0;
>>>> +}
>>>> +
>>>> +static int be_stream_wait_io(struct xen_drm_front_evtchnl *evtchnl)
>>>> +{
>>>> + if (wait_for_completion_timeout(&evtchnl->u.req.completion,
>>>> + msecs_to_jiffies(VDRM_WAIT_BACK_MS)) <= 0)
>>>> + return -ETIMEDOUT;
>>>> +
>>>> + return evtchnl->u.req.resp_status;
>>>> +}
>>>> +
>>>> static int be_mode_set(struct xen_drm_front_drm_pipeline *pipeline, uint32_t x,
>>>> uint32_t y, uint32_t width, uint32_t height, uint32_t bpp,
>>>> uint64_t fb_cookie)
>>>> {
>>>> - return 0;
>>>> + struct xen_drm_front_evtchnl *evtchnl;
>>>> + struct xen_drm_front_info *front_info;
>>>> + struct xendispl_req *req;
>>>> + unsigned long flags;
>>>> + int ret;
>>>> +
>>>> + front_info = pipeline->drm_info->front_info;
>>>> + evtchnl = &front_info->evt_pairs[pipeline->index].req;
>>>> + if (unlikely(!evtchnl))
>>>> + return -EIO;
>>>> +
>>>> + mutex_lock(&front_info->req_io_lock);
>>>> +
>>>> + spin_lock_irqsave(&front_info->io_lock, flags);
>>>> + req = be_prepare_req(evtchnl, XENDISPL_OP_SET_CONFIG);
>>>> + req->op.set_config.x = x;
>>>> + req->op.set_config.y = y;
>>>> + req->op.set_config.width = width;
>>>> + req->op.set_config.height = height;
>>>> + req->op.set_config.bpp = bpp;
>>>> + req->op.set_config.fb_cookie = fb_cookie;
>>>> +
>>>> + ret = be_stream_do_io(evtchnl, req);
>>>> + spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> + if (ret == 0)
>>>> + ret = be_stream_wait_io(evtchnl);
>>>> +
>>>> + mutex_unlock(&front_info->req_io_lock);
>>>> + return ret;
>>>> }
>>>> static int be_dbuf_create_int(struct xen_drm_front_info *front_info,
>>>> @@ -44,7 +178,69 @@ static int be_dbuf_create_int(struct xen_drm_front_info *front_info,
>>>> uint32_t bpp, uint64_t size, struct page **pages,
>>>> struct sg_table *sgt)
>>>> {
>>>> + struct xen_drm_front_evtchnl *evtchnl;
>>>> + struct xen_drm_front_shbuf *shbuf;
>>>> + struct xendispl_req *req;
>>>> + struct xen_drm_front_shbuf_cfg buf_cfg;
>>>> + unsigned long flags;
>>>> + int ret;
>>>> +
>>>> + evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
>>>> + if (unlikely(!evtchnl))
>>>> + return -EIO;
>>>> +
>>>> + memset(&buf_cfg, 0, sizeof(buf_cfg));
>>>> + buf_cfg.xb_dev = front_info->xb_dev;
>>>> + buf_cfg.pages = pages;
>>>> + buf_cfg.size = size;
>>>> + buf_cfg.sgt = sgt;
>>>> + buf_cfg.be_alloc = front_info->cfg.be_alloc;
>>>> +
>>>> + shbuf = xen_drm_front_shbuf_alloc(&buf_cfg);
>>>> + if (!shbuf)
>>>> + return -ENOMEM;
>>>> +
>>>> + ret = dbuf_add_to_list(front_info, shbuf, dbuf_cookie);
>>>> + if (ret < 0) {
>>>> + xen_drm_front_shbuf_free(shbuf);
>>>> + return ret;
>>>> + }
>>>> +
>>>> + mutex_lock(&front_info->req_io_lock);
>>>> +
>>>> + spin_lock_irqsave(&front_info->io_lock, flags);
>>>> + req = be_prepare_req(evtchnl, XENDISPL_OP_DBUF_CREATE);
>>>> + req->op.dbuf_create.gref_directory =
>>>> + xen_drm_front_shbuf_get_dir_start(shbuf);
>>>> + req->op.dbuf_create.buffer_sz = size;
>>>> + req->op.dbuf_create.dbuf_cookie = dbuf_cookie;
>>>> + req->op.dbuf_create.width = width;
>>>> + req->op.dbuf_create.height = height;
>>>> + req->op.dbuf_create.bpp = bpp;
>>>> + if (buf_cfg.be_alloc)
>>>> + req->op.dbuf_create.flags |= XENDISPL_DBUF_FLG_REQ_ALLOC;
>>>> +
>>>> + ret = be_stream_do_io(evtchnl, req);
>>>> + spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> + if (ret < 0)
>>>> + goto fail;
>>>> +
>>>> + ret = be_stream_wait_io(evtchnl);
>>>> + if (ret < 0)
>>>> + goto fail;
>>>> +
>>>> + ret = xen_drm_front_shbuf_map(shbuf);
>>>> + if (ret < 0)
>>>> + goto fail;
>>>> +
>>>> + mutex_unlock(&front_info->req_io_lock);
>>>> return 0;
>>>> +
>>>> +fail:
>>>> + mutex_unlock(&front_info->req_io_lock);
>>>> + dbuf_free(&front_info->dbuf_list, dbuf_cookie);
>>>> + return ret;
>>>> }
>>>> static int be_dbuf_create_from_sgt(struct xen_drm_front_info *front_info,
>>>> @@ -66,26 +262,144 @@ static int be_dbuf_create_from_pages(struct xen_drm_front_info *front_info,
>>>> static int be_dbuf_destroy(struct xen_drm_front_info *front_info,
>>>> uint64_t dbuf_cookie)
>>>> {
>>>> - return 0;
>>>> + struct xen_drm_front_evtchnl *evtchnl;
>>>> + struct xendispl_req *req;
>>>> + unsigned long flags;
>>>> + bool be_alloc;
>>>> + int ret;
>>>> +
>>>> + evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
>>>> + if (unlikely(!evtchnl))
>>>> + return -EIO;
>>>> +
>>>> + be_alloc = front_info->cfg.be_alloc;
>>>> +
>>>> + /*
>>>> + * for the backend allocated buffer release references now, so backend
>>>> + * can free the buffer
>>>> + */
>>>> + if (be_alloc)
>>>> + dbuf_free(&front_info->dbuf_list, dbuf_cookie);
>>>> +
>>>> + mutex_lock(&front_info->req_io_lock);
>>>> +
>>>> + spin_lock_irqsave(&front_info->io_lock, flags);
>>>> + req = be_prepare_req(evtchnl, XENDISPL_OP_DBUF_DESTROY);
>>>> + req->op.dbuf_destroy.dbuf_cookie = dbuf_cookie;
>>>> +
>>>> + ret = be_stream_do_io(evtchnl, req);
>>>> + spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> + if (ret == 0)
>>>> + ret = be_stream_wait_io(evtchnl);
>>>> +
>>>> + /*
>>>> + * do this regardless of communication status with the backend:
>>>> + * if we cannot remove remote resources remove what we can locally
>>>> + */
>>>> + if (!be_alloc)
>>>> + dbuf_free(&front_info->dbuf_list, dbuf_cookie);
>>>> +
>>>> + mutex_unlock(&front_info->req_io_lock);
>>>> + return ret;
>>>> }
>>>> static int be_fb_attach(struct xen_drm_front_info *front_info,
>>>> uint64_t dbuf_cookie, uint64_t fb_cookie, uint32_t width,
>>>> uint32_t height, uint32_t pixel_format)
>>>> {
>>>> - return 0;
>>>> + struct xen_drm_front_evtchnl *evtchnl;
>>>> + struct xen_drm_front_dbuf *buf;
>>>> + struct xendispl_req *req;
>>>> + unsigned long flags;
>>>> + int ret;
>>>> +
>>>> + evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
>>>> + if (unlikely(!evtchnl))
>>>> + return -EIO;
>>>> +
>>>> + buf = dbuf_get(&front_info->dbuf_list, dbuf_cookie);
>>>> + if (!buf)
>>>> + return -EINVAL;
>>>> +
>>>> + buf->fb_cookie = fb_cookie;
>>>> +
>>>> + mutex_lock(&front_info->req_io_lock);
>>>> +
>>>> + spin_lock_irqsave(&front_info->io_lock, flags);
>>>> + req = be_prepare_req(evtchnl, XENDISPL_OP_FB_ATTACH);
>>>> + req->op.fb_attach.dbuf_cookie = dbuf_cookie;
>>>> + req->op.fb_attach.fb_cookie = fb_cookie;
>>>> + req->op.fb_attach.width = width;
>>>> + req->op.fb_attach.height = height;
>>>> + req->op.fb_attach.pixel_format = pixel_format;
>>>> +
>>>> + ret = be_stream_do_io(evtchnl, req);
>>>> + spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> + if (ret == 0)
>>>> + ret = be_stream_wait_io(evtchnl);
>>>> +
>>>> + mutex_unlock(&front_info->req_io_lock);
>>>> + return ret;
>>>> }
>>>> static int be_fb_detach(struct xen_drm_front_info *front_info,
>>>> uint64_t fb_cookie)
>>>> {
>>>> - return 0;
>>>> + struct xen_drm_front_evtchnl *evtchnl;
>>>> + struct xendispl_req *req;
>>>> + unsigned long flags;
>>>> + int ret;
>>>> +
>>>> + evtchnl = &front_info->evt_pairs[GENERIC_OP_EVT_CHNL].req;
>>>> + if (unlikely(!evtchnl))
>>>> + return -EIO;
>>>> +
>>>> + mutex_lock(&front_info->req_io_lock);
>>>> +
>>>> + spin_lock_irqsave(&front_info->io_lock, flags);
>>>> + req = be_prepare_req(evtchnl, XENDISPL_OP_FB_DETACH);
>>>> + req->op.fb_detach.fb_cookie = fb_cookie;
>>>> +
>>>> + ret = be_stream_do_io(evtchnl, req);
>>>> + spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> + if (ret == 0)
>>>> + ret = be_stream_wait_io(evtchnl);
>>>> +
>>>> + mutex_unlock(&front_info->req_io_lock);
>>>> + return ret;
>>>> }
>>>> static int be_page_flip(struct xen_drm_front_info *front_info, int conn_idx,
>>>> uint64_t fb_cookie)
>>>> {
>>>> - return 0;
>>>> + struct xen_drm_front_evtchnl *evtchnl;
>>>> + struct xendispl_req *req;
>>>> + unsigned long flags;
>>>> + int ret;
>>>> +
>>>> + if (unlikely(conn_idx >= front_info->num_evt_pairs))
>>>> + return -EINVAL;
>>>> +
>>>> + dbuf_flush_fb(&front_info->dbuf_list, fb_cookie);
>>>> + evtchnl = &front_info->evt_pairs[conn_idx].req;
>>>> +
>>>> + mutex_lock(&front_info->req_io_lock);
>>>> +
>>>> + spin_lock_irqsave(&front_info->io_lock, flags);
>>>> + req = be_prepare_req(evtchnl, XENDISPL_OP_PG_FLIP);
>>>> + req->op.pg_flip.fb_cookie = fb_cookie;
>>>> +
>>>> + ret = be_stream_do_io(evtchnl, req);
>>>> + spin_unlock_irqrestore(&front_info->io_lock, flags);
>>>> +
>>>> + if (ret == 0)
>>>> + ret = be_stream_wait_io(evtchnl);
>>>> +
>>>> + mutex_unlock(&front_info->req_io_lock);
>>>> + return ret;
>>>> }
>>>> static void xen_drm_drv_unload(struct xen_drm_front_info *front_info)
>>>> @@ -183,6 +497,7 @@ static void xen_drv_remove_internal(struct xen_drm_front_info *front_info)
>>>> {
>>>> xen_drm_drv_deinit(front_info);
>>>> xen_drm_front_evtchnl_free_all(front_info);
>>>> + dbuf_free_all(&front_info->dbuf_list);
>>>> }
>>>> static int backend_on_initwait(struct xen_drm_front_info *front_info)
>>>> @@ -310,6 +625,8 @@ static int xen_drv_probe(struct xenbus_device *xb_dev,
>>>> front_info->xb_dev = xb_dev;
>>>> spin_lock_init(&front_info->io_lock);
>>>> + mutex_init(&front_info->req_io_lock);
>>>> + INIT_LIST_HEAD(&front_info->dbuf_list);
>>>> front_info->drm_pdrv_registered = false;
>>>> dev_set_drvdata(&xb_dev->dev, front_info);
>>>> return xenbus_switch_state(xb_dev, XenbusStateInitialising);
>>>> diff --git a/drivers/gpu/drm/xen/xen_drm_front.h b/drivers/gpu/drm/xen/xen_drm_front.h
>>>> index c6f52c892434..db32d00145d1 100644
>>>> --- a/drivers/gpu/drm/xen/xen_drm_front.h
>>>> +++ b/drivers/gpu/drm/xen/xen_drm_front.h
>>>> @@ -137,6 +137,8 @@ struct xen_drm_front_info {
>>>> struct xenbus_device *xb_dev;
>>>> /* to protect data between backend IO code and interrupt handler */
>>>> spinlock_t io_lock;
>>>> + /* serializer for backend IO: request/response */
>>>> + struct mutex req_io_lock;
>>>> bool drm_pdrv_registered;
>>>> /* virtual DRM platform device */
>>>> struct platform_device *drm_pdev;
>>>> @@ -144,6 +146,9 @@ struct xen_drm_front_info {
>>>> int num_evt_pairs;
>>>> struct xen_drm_front_evtchnl_pair *evt_pairs;
>>>> struct xen_drm_front_cfg cfg;
>>>> +
>>>> + /* display buffers */
>>>> + struct list_head dbuf_list;
>>>> };
>>>> #endif /* __XEN_DRM_FRONT_H_ */
>>>> --
>>>> 2.7.4
>>>>
>>>> _______________________________________________
>>>> dri-devel mailing list
>>>> [email protected]
>>>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>> _______________________________________________
>> dri-devel mailing list
>> [email protected]
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel