Re: [PATCH 2/9] drm/xen-front: Implement Xen bus state handling

On 21/02/18 09:03, Oleksandr Andrushchenko wrote:

From: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com

Initial handling for Xen bus states: implement Xen bus state machine for the frontend driver according to the state diagram and recovery flow from display para-virtualized protocol: xen/interface/io/displif.h.

Signed-off-by: Oleksandr Andrushchenko oleksandr_andrushchenko@epam.com

drivers/gpu/drm/xen/xen_drm_front.c | 124 +++++++++++++++++++++++++++++++++++- drivers/gpu/drm/xen/xen_drm_front.h | 26 ++++++++ 2 files changed, 149 insertions(+), 1 deletion(-) create mode 100644 drivers/gpu/drm/xen/xen_drm_front.h

diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c index fd372fb464a1..d0306f9d660d 100644 --- a/drivers/gpu/drm/xen/xen_drm_front.c +++ b/drivers/gpu/drm/xen/xen_drm_front.c @@ -24,19 +24,141 @@

#include <xen/interface/io/displif.h>

+#include "xen_drm_front.h"

+static void xen_drv_remove_internal(struct xen_drm_front_info *front_info) +{ +}

+static int backend_on_initwait(struct xen_drm_front_info *front_info) +{

• return 0;

+}

+static int backend_on_connected(struct xen_drm_front_info *front_info) +{

• return 0;

+}

+static void backend_on_disconnected(struct xen_drm_front_info *front_info) +{

• xenbus_switch_state(front_info->xb_dev, XenbusStateInitialising);

+}

static void backend_on_changed(struct xenbus_device *xb_dev, enum xenbus_state backend_state) {

• struct xen_drm_front_info *front_info = dev_get_drvdata(&xb_dev->dev);
• int ret;
• DRM_DEBUG("Backend state is %s, front is %s\n",

• 	xenbus_strstate(backend_state),
  

• 	xenbus_strstate(xb_dev->state));
  

• switch (backend_state) {
• case XenbusStateReconfiguring:

• /* fall through */
  

• case XenbusStateReconfigured:

• /* fall through */
  

• case XenbusStateInitialised:

• break;
  

• case XenbusStateInitialising:

• /* recovering after backend unexpected closure */
  

• backend_on_disconnected(front_info);
  

• break;
  

• case XenbusStateInitWait:

• /* recovering after backend unexpected closure */
  

• backend_on_disconnected(front_info);
  

• if (xb_dev->state != XenbusStateInitialising)
  

• 	break;
  

• ret = backend_on_initwait(front_info);
  

• if (ret < 0)
  

• 	xenbus_dev_fatal(xb_dev, ret, "initializing frontend");
  

• else
  

• 	xenbus_switch_state(xb_dev, XenbusStateInitialised);
  

• break;
  

• case XenbusStateConnected:

• if (xb_dev->state != XenbusStateInitialised)
  

• 	break;
  

• ret = backend_on_connected(front_info);
  

• if (ret < 0)
  

• 	xenbus_dev_fatal(xb_dev, ret, "initializing DRM driver");
  

• else
  

• 	xenbus_switch_state(xb_dev, XenbusStateConnected);
  

• break;
  

• case XenbusStateClosing:

• /*
  

•  * in this state backend starts freeing resources,
  

•  * so let it go into closed state, so we can also
  

•  * remove ours
  

•  */
  

• break;
  

• case XenbusStateUnknown:

• /* fall through */
  

• case XenbusStateClosed:

• if (xb_dev->state == XenbusStateClosed)
  

• 	break;
  

• backend_on_disconnected(front_info);
  

• break;
  

• }

}

static int xen_drv_probe(struct xenbus_device *xb_dev, const struct xenbus_device_id *id) {

• return 0;

• struct xen_drm_front_info *front_info;
• front_info = devm_kzalloc(&xb_dev->dev,

• 	sizeof(*front_info), GFP_KERNEL);
  

• if (!front_info) {

• xenbus_dev_fatal(xb_dev, -ENOMEM, "allocating device memory");
  

No need for message in case of allocation failure: this is handled in memory allocation already.

Juergen