linux-kernel - [PATCH net-next 2/2] net: ipa: only reset channel twice for IPA v3.5.1

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Date:   Mon,  4 May 2020 18:30:03 -0500
From:   Alex Elder <elder@...aro.org>
To:     davem@...emloft.net
Cc:     evgreen@...omium.org, subashab@...eaurora.org,
        cpratapa@...eaurora.org, bjorn.andersson@...aro.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net-next 2/2] net: ipa: only reset channel twice for IPA v3.5.1

In gsi_channel_reset(), RX channels are subjected to two consecutive
CHANNEL_RESET commands.  This workaround should only be used for IPA
version 3.5.1, and for newer hardware "can lead to unwanted behavior."

Only issue the second CHANNEL_RESET command for legacy hardware.

Signed-off-by: Alex Elder <elder@...aro.org>
---
 drivers/net/ipa/gsi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ipa/gsi.c b/drivers/net/ipa/gsi.c
index cd5d8045c7e5..8ccbbb920c11 100644
--- a/drivers/net/ipa/gsi.c
+++ b/drivers/net/ipa/gsi.c
@@ -840,9 +840,9 @@ void gsi_channel_reset(struct gsi *gsi, u32 channel_id, bool legacy)
 
 	mutex_lock(&gsi->mutex);
 
-	/* Due to a hardware quirk we need to reset RX channels twice. */
 	gsi_channel_reset_command(channel);
-	if (!channel->toward_ipa)
+	/* Due to a hardware quirk we may need to reset RX channels twice. */
+	if (legacy && !channel->toward_ipa)
 		gsi_channel_reset_command(channel);
 
 	gsi_channel_program(channel, legacy);
-- 
2.20.1