[Intel-gfx] [PATCH v4 08/13] drm/i915/guc: Implement response handling in send_ct()

[Jani Nikula]

On Mon, 26 Mar 2018, Michał Winiarski <michal.winiarski at intel.com> wrote:
> On Fri, Mar 23, 2018 at 02:47:23PM +0000, Michal Wajdeczko wrote:
>> Instead of returning small data in response status dword,
>> GuC may append longer data as response message payload.
>> If caller provides response buffer, we will copy received
>> data and use number of received data dwords as new success
>> return value. We will WARN if response from GuC does not
>> match caller expectation.
>> 
>> v2: fix timeout and checkpatch warnings (Michal)
>> 
>> Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
>> Cc: Oscar Mateo <oscar.mateo at intel.com>
>> Cc: Michel Thierry <michel.thierry at intel.com>
>> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
>> ---
>>  drivers/gpu/drm/i915/intel_guc_ct.c | 137 ++++++++++++++++++++++++++++++++----
>>  drivers/gpu/drm/i915/intel_guc_ct.h |   5 ++
>>  2 files changed, 128 insertions(+), 14 deletions(-)
>> 
>
> [SNIP]
>
>> @@ -418,13 +499,15 @@ static int ctch_send(struct intel_guc *guc,
>>  static int intel_guc_send_ct(struct intel_guc *guc, const u32 *action, u32 len,
>>  			     u32 *response_buf, u32 response_buf_size)
>>  {
>> -	struct intel_guc_ct_channel *ctch = &guc->ct.host_channel;
>> +	struct intel_guc_ct *ct = &guc->ct;
>> +	struct intel_guc_ct_channel *ctch = &ct->host_channel;
>>  	u32 status = ~0; /* undefined */
>>  	int ret;
>>  
>>  	mutex_lock(&guc->send_mutex);
>>  
>> -	ret = ctch_send(guc, ctch, action, len, &status);
>> +	ret = ctch_send(ct, ctch, action, len, response_buf, response_buf_size,
>> +			&status);
>>  	if (unlikely(ret < 0)) {
>>  		DRM_ERROR("CT: send action %#X failed; err=%d status=%#X\n",
>>  			  action[0], ret, status);
>> @@ -503,8 +586,13 @@ static int ctb_read(struct intel_guc_ct_buffer *ctb, u32 *data)
>>  static int ct_handle_response(struct intel_guc_ct *ct, const u32 *msg)
>>  {
>>  	u32 header = msg[0];
>> +	u32 fence = msg[1];
>>  	u32 status = msg[2];
>>  	u32 len = ct_header_get_len(header) + 1; /* total len with header */
>> +	u32 payload_len = len - 3; /* len<3 is treated as protocol error */
>
> Magic numbers, please ether define 3 as min payload length or hide this behind
> macro.

And check len >= 3 before substracting 3.

BR,
Jani.


>
>> +	struct ct_request *req;
>> +	bool found = false;
>> +	unsigned long flags;
>>  
>>  	GEM_BUG_ON(!ct_header_is_response(header));
>>  
>> @@ -518,8 +606,29 @@ static int ct_handle_response(struct intel_guc_ct *ct, const u32 *msg)
>>  		DRM_ERROR("CT: corrupted response %*phn\n", 4*len, msg);
>>  		return -EPROTO;
>>  	}
>> +	spin_lock_irqsave(&ct->lock, flags);
>
> Isn't this called from the irq? We can use plain spin_lock here.
>
>> +	list_for_each_entry(req, &ct->pending_requests, link) {
>> +		if (req->fence != fence) {
>> +			DRM_DEBUG_DRIVER("CT: request %u awaits response\n",
>> +					 req->fence);
>> +			continue;
>
> Is this expected?
> In other words - do we expect out of order responses?
> Can we extract this into a helper (find request)?
>
> -Michał
>
>> +		}
>> +		if (unlikely(payload_len > req->response_len)) {
>> +			DRM_ERROR("CT: response %u too long %*phn\n",
>> +				  req->fence, 4*len, msg);
>> +			payload_len = 0;
>> +		}
>> +		if (payload_len)
>> +			memcpy(req->response_buf, msg + 3, 4*payload_len);
>> +		req->response_len = payload_len;
>> +		WRITE_ONCE(req->status, status);
>> +		found = true;
>> +		break;
>> +	}
>> +	spin_unlock_irqrestore(&ct->lock, flags);
>>  
>> -	/* XXX */
>> +	if (!found)
>> +		DRM_ERROR("CT: unsolicited response %*phn\n", 4*len, msg);
>>  	return 0;
>>  }
>>  
>> diff --git a/drivers/gpu/drm/i915/intel_guc_ct.h b/drivers/gpu/drm/i915/intel_guc_ct.h
>> index 595c8ad..905566b 100644
>> --- a/drivers/gpu/drm/i915/intel_guc_ct.h
>> +++ b/drivers/gpu/drm/i915/intel_guc_ct.h
>> @@ -71,10 +71,15 @@ struct intel_guc_ct_channel {
>>  /** Holds all command transport channels.
>>   *
>>   * @host_channel: main channel used by the host
>> + * @lock: spin lock for pending requests list
>> + * @pending_requests: list of pending requests
>>   */
>>  struct intel_guc_ct {
>>  	struct intel_guc_ct_channel host_channel;
>>  	/* other channels are tbd */
>> +
>> +	spinlock_t lock;
>> +	struct list_head pending_requests;
>>  };
>>  
>>  void intel_guc_ct_init_early(struct intel_guc_ct *ct);
>> -- 
>> 1.9.1
>> 
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-- 
Jani Nikula, Intel Open Source Technology Center