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From:   Ravulapati Vishnu vardhan rao 
        <Vishnuvardhanrao.Ravulapati@amd.com>
CC:     <Alexander.Deucher@amd.com>,
        Ravulapati Vishnu vardhan rao 
        <Vishnuvardhanrao.Ravulapati@amd.com>,
        Liam Girdwood <lgirdwood@gmail.com>,
        Mark Brown <broonie@kernel.org>,
        Jaroslav Kysela <perex@perex.cz>,
        "Takashi Iwai" <tiwai@suse.com>,
        Akshu Agrawal <akshu.agrawal@amd.com>,
        Dan Carpenter <dan.carpenter@oracle.com>,
        Vijendar Mukunda <Vijendar.Mukunda@amd.com>,
        "moderated list:SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEM..." 
        <alsa-devel@alsa-project.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: [PATCH] ASoC: amd:Replacing MSI with Legacy IRQ model
Date:   Tue, 22 Dec 2020 17:29:18 +0530
Message-ID: <20201222115929.11222-1-Vishnuvardhanrao.Ravulapati@amd.com>
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When we try to play and capture simultaneously we see that
interrupts are genrated but our handler is not being acknowledged,
After investigating further more in detail on this issue we found
that IRQ delivery via MSI from the ACP IP is unreliable and so sometimes
interrupt generated will not be acknowledged so MSI model shouldn't be used
and using legacy IRQs will resolve interrupt handling issue.

This patch replaces MSI interrupt handling with legacy IRQ model.

Issue can be reproduced easily by running below python script:

import subprocess
import time
import threading

def do2():
  cmd = 'aplay -f dat -D hw:2,1 /dev/zero -d 1'
    subprocess.call(cmd, stdin=subprocess.PIPE,
			stderr=subprocess.PIPE, shell=True)
    print('Play Done')

def run():
	for i in range(1000):
		do2()

def do(i):
    cmd = 'arecord -f dat -D hw:2,2 /dev/null -d 1'
    subprocess.call(cmd, stdout=subprocess.PIPE,
			stderr=subprocess.PIPE, shell=True)
    print(datetime.datetime.now(), i)

t = threading.Thread(target=run)
t.start()
for i in range(1000):
	do(i)

t.join()

After applying this patch issue is resolved.

Signed-off-by: Ravulapati Vishnu vardhan rao <Vishnuvardhanrao.Ravulapati@amd.com>
---
 sound/soc/amd/raven/pci-acp3x.c | 16 +++-------------
 1 file changed, 3 insertions(+), 13 deletions(-)

diff --git a/sound/soc/amd/raven/pci-acp3x.c b/sound/soc/amd/raven/pci-acp3x.c
index 8c138e490f0c..d3536fd6a124 100644
--- a/sound/soc/amd/raven/pci-acp3x.c
+++ b/sound/soc/amd/raven/pci-acp3x.c
@@ -140,21 +140,14 @@ static int snd_acp3x_probe(struct pci_dev *pci,
 		goto release_regions;
 	}
 
-	/* check for msi interrupt support */
-	ret = pci_enable_msi(pci);
-	if (ret)
-		/* msi is not enabled */
-		irqflags = IRQF_SHARED;
-	else
-		/* msi is enabled */
-		irqflags = 0;
+	irqflags = IRQF_SHARED;
 
 	addr = pci_resource_start(pci, 0);
 	adata->acp3x_base = devm_ioremap(&pci->dev, addr,
 					pci_resource_len(pci, 0));
 	if (!adata->acp3x_base) {
 		ret = -ENOMEM;
-		goto disable_msi;
+		goto release_regions;
 	}
 	pci_set_master(pci);
 	pci_set_drvdata(pci, adata);
@@ -162,7 +155,7 @@ static int snd_acp3x_probe(struct pci_dev *pci,
 	adata->pme_en = rv_readl(adata->acp3x_base + mmACP_PME_EN);
 	ret = acp3x_init(adata);
 	if (ret)
-		goto disable_msi;
+		goto release_regions;
 
 	val = rv_readl(adata->acp3x_base + mmACP_I2S_PIN_CONFIG);
 	switch (val) {
@@ -251,8 +244,6 @@ static int snd_acp3x_probe(struct pci_dev *pci,
 de_init:
 	if (acp3x_deinit(adata->acp3x_base))
 		dev_err(&pci->dev, "ACP de-init failed\n");
-disable_msi:
-	pci_disable_msi(pci);
 release_regions:
 	pci_release_regions(pci);
 disable_pci:
@@ -311,7 +302,6 @@ static void snd_acp3x_remove(struct pci_dev *pci)
 		dev_err(&pci->dev, "ACP de-init failed\n");
 	pm_runtime_forbid(&pci->dev);
 	pm_runtime_get_noresume(&pci->dev);
-	pci_disable_msi(pci);
 	pci_release_regions(pci);
 	pci_disable_device(pci);
 }
-- 
2.17.1