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SubjectRe: [PATCH 2/9] drm/xen-front: Implement Xen bus state handling
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On 02/21/2018 10:23 AM, Juergen Gross wrote:
> 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.
Will remove, thank you
>
> Juergen

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