linux-kernel - [PATCH net 2/2] net: ipa: disable HOLB drop when updating timer

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Date:   Fri, 12 Nov 2021 16:22:10 -0600
From:   Alex Elder <elder@...aro.org>
To:     davem@...emloft.net, kuba@...nel.org
Cc:     pkurapat@...eaurora.org, avuyyuru@...eaurora.org,
        bjorn.andersson@...aro.org, cpratapa@...eaurora.org,
        subashab@...eaurora.org, evgreen@...omium.org, elder@...nel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH net 2/2] net: ipa: disable HOLB drop when updating timer

The head-of-line blocking timer should only be modified when
head-of-line drop is disabled.

One of the steps in recovering from a modem crash is to enable
dropping of packets with timeout of 0 (immediate).  We don't know
how the modem configured its endpoints, so before we program the
timer, we need to ensure HOL_BLOCK is disabled.

Fixes: 84f9bd12d46db ("soc: qcom: ipa: IPA endpoints")
Signed-off-by: Alex Elder <elder@...aro.org>
---
 drivers/net/ipa/ipa_endpoint.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ipa/ipa_endpoint.c b/drivers/net/ipa/ipa_endpoint.c
index 006da4642a0ba..ef790fd0ab56a 100644
--- a/drivers/net/ipa/ipa_endpoint.c
+++ b/drivers/net/ipa/ipa_endpoint.c
@@ -853,6 +853,7 @@ static void ipa_endpoint_init_hol_block_timer(struct ipa_endpoint *endpoint,
 	u32 offset;
 	u32 val;
 
+	/* This should only be changed when HOL_BLOCK_EN is disabled */
 	offset = IPA_REG_ENDP_INIT_HOL_BLOCK_TIMER_N_OFFSET(endpoint_id);
 	val = hol_block_timer_val(ipa, microseconds);
 	iowrite32(val, ipa->reg_virt + offset);
@@ -883,6 +884,7 @@ void ipa_endpoint_modem_hol_block_clear_all(struct ipa *ipa)
 		if (endpoint->toward_ipa || endpoint->ee_id != GSI_EE_MODEM)
 			continue;
 
+		ipa_endpoint_init_hol_block_enable(endpoint, false);
 		ipa_endpoint_init_hol_block_timer(endpoint, 0);
 		ipa_endpoint_init_hol_block_enable(endpoint, true);
 	}
-- 
2.32.0