linux-kernel - [PATCH net-next v2 4/9] net: ipa: kill gsi_trans_commit_wait

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Date:   Sat, 21 May 2022 19:32:18 -0500
From:   Alex Elder <elder@...aro.org>
To:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com
Cc:     mka@...omium.org, evgreen@...omium.org, bjorn.andersson@...aro.org,
        quic_cpratapa@...cinc.com, quic_avuyyuru@...cinc.com,
        quic_jponduru@...cinc.com, quic_subashab@...cinc.com,
        elder@...nel.org, netdev@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net-next v2 4/9] net: ipa: kill gsi_trans_commit_wait_timeout()

Since the beginning gsi_trans_commit_wait_timeout() has existed to
provide a way to allow waiting a limited time for a transaction
to complete.  But that function has never been used.

In fact, there is no use for this function, because a transaction
committed to hardware should *always* complete.  The only reason it
might not complete is if there were a hardware failure, or perhaps a
system configuration error.

Furthermore, if a timeout ever did occur, the IPA hardware would be
in an indeterminate state, from which there is no recovery.  It
would require some sort of complete IPA reset, and would require the
participation of the modem, and at this time there is no such
sequence defined.

So get rid of the definition of gsi_trans_commit_wait_timeout(), and
update a few comments accordingly.

Signed-off-by: Alex Elder <elder@...aro.org>
---
 drivers/net/ipa/gsi_trans.c    | 22 ----------------------
 drivers/net/ipa/gsi_trans.h    |  9 ---------
 drivers/net/ipa/ipa_cmd.c      | 15 +++++++--------
 drivers/net/ipa/ipa_endpoint.c |  1 -
 4 files changed, 7 insertions(+), 40 deletions(-)

diff --git a/drivers/net/ipa/gsi_trans.c b/drivers/net/ipa/gsi_trans.c
index 87e1d43c118c1..bf31ef3d56adc 100644
--- a/drivers/net/ipa/gsi_trans.c
+++ b/drivers/net/ipa/gsi_trans.c
@@ -637,28 +637,6 @@ void gsi_trans_commit_wait(struct gsi_trans *trans)
 	gsi_trans_free(trans);
 }
 
-/* Commit a GSI transaction and wait for it to complete, with timeout */
-int gsi_trans_commit_wait_timeout(struct gsi_trans *trans,
-				  unsigned long timeout)
-{
-	unsigned long timeout_jiffies = msecs_to_jiffies(timeout);
-	unsigned long remaining = 1;	/* In case of empty transaction */
-
-	if (!trans->used)
-		goto out_trans_free;
-
-	refcount_inc(&trans->refcount);
-
-	__gsi_trans_commit(trans, true);
-
-	remaining = wait_for_completion_timeout(&trans->completion,
-						timeout_jiffies);
-out_trans_free:
-	gsi_trans_free(trans);
-
-	return remaining ? 0 : -ETIMEDOUT;
-}
-
 /* Process the completion of a transaction; called while polling */
 void gsi_trans_complete(struct gsi_trans *trans)
 {
diff --git a/drivers/net/ipa/gsi_trans.h b/drivers/net/ipa/gsi_trans.h
index af379b49299ee..387ea50dd039e 100644
--- a/drivers/net/ipa/gsi_trans.h
+++ b/drivers/net/ipa/gsi_trans.h
@@ -205,15 +205,6 @@ void gsi_trans_commit(struct gsi_trans *trans, bool ring_db);
  */
 void gsi_trans_commit_wait(struct gsi_trans *trans);
 
-/**
- * gsi_trans_commit_wait_timeout() - Commit a GSI transaction and wait for
- *				     it to complete, with timeout
- * @trans:	Transaction to commit
- * @timeout:	Timeout period (in milliseconds)
- */
-int gsi_trans_commit_wait_timeout(struct gsi_trans *trans,
-				  unsigned long timeout);
-
 /**
  * gsi_trans_read_byte() - Issue a single byte read TRE on a channel
  * @gsi:	GSI pointer
diff --git a/drivers/net/ipa/ipa_cmd.c b/drivers/net/ipa/ipa_cmd.c
index d57472ea077f2..77b84cea6e68f 100644
--- a/drivers/net/ipa/ipa_cmd.c
+++ b/drivers/net/ipa/ipa_cmd.c
@@ -26,14 +26,13 @@
  * other than data transfer to another endpoint.
  *
  * Immediate commands are represented by GSI transactions just like other
- * transfer requests, represented by a single GSI TRE.  Each immediate
- * command has a well-defined format, having a payload of a known length.
- * This allows the transfer element's length field to be used to hold an
- * immediate command's opcode.  The payload for a command resides in DRAM
- * and is described by a single scatterlist entry in its transaction.
- * Commands do not require a transaction completion callback.  To commit
- * an immediate command transaction, either gsi_trans_commit_wait() or
- * gsi_trans_commit_wait_timeout() is used.
+ * transfer requests, and use a single GSI TRE.  Each immediate command
+ * has a well-defined format, having a payload of a known length.  This
+ * allows the transfer element's length field to be used to hold an
+ * immediate command's opcode.  The payload for a command resides in AP
+ * memory and is described by a single scatterlist entry in its transaction.
+ * Commands do not require a transaction completion callback, and are
+ * (currently) always issued using gsi_trans_commit_wait().
  */
 
 /* Some commands can wait until indicated pipeline stages are clear */
diff --git a/drivers/net/ipa/ipa_endpoint.c b/drivers/net/ipa/ipa_endpoint.c
index 586529511cf6b..5ed5b8fd3ea36 100644
--- a/drivers/net/ipa/ipa_endpoint.c
+++ b/drivers/net/ipa/ipa_endpoint.c
@@ -478,7 +478,6 @@ int ipa_endpoint_modem_exception_reset_all(struct ipa *ipa)
 
 	ipa_cmd_pipeline_clear_add(trans);
 
-	/* XXX This should have a 1 second timeout */
 	gsi_trans_commit_wait(trans);
 
 	ipa_cmd_pipeline_clear_wait(ipa);
-- 
2.32.0