GuC can respond to our commands not only by updating SEND buffer
descriptor, but can also send a response message over RECV buffer.
Guc can also send unsolicited request messages over RECV buffer.
Let's start reading those messages and make placeholders
for actual response/request handlers.
v2: misc improvements (Michal)
v3: change response detection (Michal)
invalid status is protocol error (Michal)
v4: rebase
v5: fix checkpatch (Michel)
don't use fields before check (Jani)
add some documentation (Michal)
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
Cc: Oscar Mateo <oscar.mateo@xxxxxxxxx>
Cc: Michel Thierry <michel.thierry@xxxxxxxxx>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
Reviewed-by: Michel Thierry <michel.thierry@xxxxxxxxx> # 4.5
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_guc_ct.c | 184 +++++++++++++++++++++++++++++++++++-
1 file changed, 183 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/i915/intel_guc_ct.c b/drivers/gpu/drm/i915/intel_guc_ct.c
index a54bf58..14f55de 100644
--- a/drivers/gpu/drm/i915/intel_guc_ct.c
+++ b/drivers/gpu/drm/i915/intel_guc_ct.c
@@ -273,6 +273,24 @@ static u32 ctch_get_next_fence(struct intel_guc_ct_channel *ctch)
return ++ctch->next_fence;
}
+/**
+ * DOC: CTB Host to GuC request
+ *
+ * Format of the CTB Host to GuC request message is as follows::
+ *
+ * +------------+---------+---------+---------+---------+
+ * | msg[0] | [1] | [2] | ... | [n-1] |
+ * +------------+---------+---------+---------+---------+
+ * | MESSAGE | MESSAGE PAYLOAD |
+ * + HEADER +---------+---------+---------+---------+
+ * | | 0 | 1 | ... | n |
+ * +============+=========+=========+=========+=========+
+ * | len >= 1 | FENCE | request specific data |
+ * +------+-----+---------+---------+---------+---------+
+ *
+ * ^-----------------len-------------------^
+ */
+
static int ctb_write(struct intel_guc_ct_buffer *ctb,
const u32 *action,
u32 len /* in dwords */,
@@ -305,7 +323,8 @@ static int ctb_write(struct intel_guc_ct_buffer *ctb,
if (unlikely(used + len + 1 >= size))
return -ENOSPC;
- /* Write the message. The format is the following:
+ /*
+ * Write the message. The format is the following:
* DW0: header (including action code)
* DW1: fence
* DW2+: action data
@@ -427,6 +446,167 @@ static int intel_guc_send_ct(struct intel_guc *guc, const u32 *action, u32 len,
return ret;
}
+static inline unsigned int ct_header_get_len(u32 header)
+{
+ return (header >> GUC_CT_MSG_LEN_SHIFT) & GUC_CT_MSG_LEN_MASK;
+}
+
+static inline unsigned int ct_header_get_action(u32 header)
+{
+ return (header >> GUC_CT_MSG_ACTION_SHIFT) & GUC_CT_MSG_ACTION_MASK;
+}
+
+static inline bool ct_header_is_response(u32 header)
+{
+ return ct_header_get_action(header) == INTEL_GUC_ACTION_DEFAULT;
+}
+
+static int ctb_read(struct intel_guc_ct_buffer *ctb, u32 *data)
+{
+ struct guc_ct_buffer_desc *desc = ctb->desc;
+ u32 head = desc->head / 4; /* in dwords */
+ u32 tail = desc->tail / 4; /* in dwords */
+ u32 size = desc->size / 4; /* in dwords */
+ u32 *cmds = ctb->cmds;
+ s32 available; /* in dwords */
+ unsigned int len;
+ unsigned int i;
+
+ GEM_BUG_ON(desc->size % 4);
+ GEM_BUG_ON(desc->head % 4);
+ GEM_BUG_ON(desc->tail % 4);
+ GEM_BUG_ON(tail >= size);
+ GEM_BUG_ON(head >= size);
+
+ /* tail == head condition indicates empty */
+ available = tail - head;
+ if (unlikely(available == 0))
+ return -ENODATA;
+
+ /* beware of buffer wrap case */
+ if (unlikely(available < 0))
+ available += size;
+ GEM_BUG_ON(available < 0);
+
+ data[0] = cmds[head];
+ head = (head + 1) % size;
+
+ /* message len with header */
+ len = ct_header_get_len(data[0]) + 1;
+ if (unlikely(len > (u32)available)) {
+ DRM_ERROR("CT: incomplete message %*phn %*phn %*phn\n",
+ 4, data,
+ 4 * (head + available - 1 > size ?
+ size - head : available - 1), &cmds[head],
+ 4 * (head + available - 1 > size ?
+ available - 1 - size + head : 0), &cmds[0]);
+ return -EPROTO;
+ }
+
+ for (i = 1; i < len; i++) {
+ data[i] = cmds[head];
+ head = (head + 1) % size;
+ }
+
+ desc->head = head * 4;
+ return 0;
+}
+
+/**
+ * DOC: CTB GuC to Host response
+ *
+ * Format of the CTB GuC to Host response message is as follows::
+ *
+ * +------------+---------+---------+---------+---------+---------+
+ * | msg[0] | [1] | [2] | [3] | ... | [n-1] |
+ * +------------+---------+---------+---------+---------+---------+
+ * | MESSAGE | MESSAGE PAYLOAD |
+ * + HEADER +---------+---------+---------+---------+---------+
+ * | | 0 | 1 | 2 | ... | n |
+ * +============+=========+=========+=========+=========+=========+
+ * | len >= 2 | FENCE | STATUS | response specific data |
+ * +------+-----+---------+---------+---------+---------+---------+
+ *
+ * ^-----------------------len-----------------------^
+ */
+
+static int ct_handle_response(struct intel_guc_ct *ct, const u32 *msg)
+{
+ u32 header = msg[0];
+ u32 len = ct_header_get_len(header);
+ u32 msglen = len + 1; /* total message length including header */
+ u32 fence;
+ u32 status;
+
+ GEM_BUG_ON(!ct_header_is_response(header));
+
+ /* Response payload shall at least include fence and status */
+ if (unlikely(len < 2)) {
+ DRM_ERROR("CT: corrupted response %*phn\n", 4 * msglen, msg);
+ return -EPROTO;
+ }
+
+ fence = msg[1];
+ status = msg[2];
+
+ /* Format of the status follows RESPONSE message */
+ if (unlikely(!INTEL_GUC_MSG_IS_RESPONSE(status))) {
+ DRM_ERROR("CT: corrupted response %*phn\n", 4 * msglen, msg);
+ return -EPROTO;
+ }
+
+ /* XXX */
+ return 0;
+}
+
+static int ct_handle_request(struct intel_guc_ct *ct, const u32 *msg)
+{
+ u32 header = msg[0];
+
+ GEM_BUG_ON(ct_header_is_response(header));
+
+ /* XXX */
+ return 0;
+}
+
+static void ct_process_host_channel(struct intel_guc_ct *ct)
+{
+ struct intel_guc_ct_channel *ctch = &ct->host_channel;
+ struct intel_guc_ct_buffer *ctb = &ctch->ctbs[CTB_RECV];
+ u32 msg[GUC_CT_MSG_LEN_MASK + 1]; /* one extra dw for the header */
+ int err = 0;
+
+ if (!ctch_is_open(ctch))
+ return;
+
+ do {
+ err = ctb_read(ctb, msg);
+ if (err)
+ break;
+
+ if (ct_header_is_response(msg[0]))
+ err = ct_handle_response(ct, msg);
+ else
+ err = ct_handle_request(ct, msg);
+ } while (!err);
+
+ if (GEM_WARN_ON(err == -EPROTO)) {
+ DRM_ERROR("CT: corrupted message detected!\n");
+ ctb->desc->is_in_error = 1;
+ }
+}
+
+/*
+ * When we're communicating with the GuC over CT, GuC uses events
+ * to notify us about new messages being posted on the RECV buffer.
+ */
+static void intel_guc_to_host_event_handler_ct(struct intel_guc *guc)
+{
+ struct intel_guc_ct *ct = &guc->ct;
+
+ ct_process_host_channel(ct);
+}
+
/**
* intel_guc_ct_enable - Enable buffer based command transport.
* @ct: pointer to CT struct
@@ -450,6 +630,7 @@ int intel_guc_ct_enable(struct intel_guc_ct *ct)
/* Switch into cmd transport buffer based send() */
guc->send = intel_guc_send_ct;
+ guc->handler = intel_guc_to_host_event_handler_ct;
DRM_INFO("CT: %s\n", enableddisabled(true));
return 0;
}
@@ -475,5 +656,6 @@ void intel_guc_ct_disable(struct intel_guc_ct *ct)
/* Disable send */
guc->send = intel_guc_send_nop;
+ guc->handler = intel_guc_to_host_event_handler_nop;
DRM_INFO("CT: %s\n", enableddisabled(false));
}
--
1.9.1
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