From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        =?UTF-8?q?Reimar=20D=C3=B6ffinger?= <Reimar.Doeffinger@gmx.de>,
        Paul Menzel <pmenzel@molgen.mpg.de>,
        Damien Le Moal <damien.lemoal@wdc.com>
Subject: [PATCH 5.4 079/355] libata: fix checking of DMA state
Date:   Mon, 15 Nov 2021 18:00:03 +0100
Message-Id: <20211115165316.359094674@linuxfoundation.org>
In-Reply-To: <20211115165313.549179499@linuxfoundation.org>
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From: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

commit f971a85439bd25dc7b4d597cf5e4e8dc7ffc884b upstream.

Checking if DMA is enabled should be done via the
ata_dma_enabled helper function, since the init state
0xff indicates disabled.
This meant that ATA_CMD_READ_LOG_DMA_EXT was used and probed
for before DMA was enabled, which caused hangs for some combinations
of controllers and devices.
It might also have caused it to be incorrectly disabled as broken,
but there have been no reports of that.

Cc: stable@vger.kernel.org
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=195895
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>
Tested-by: Paul Menzel <pmenzel@molgen.mpg.de>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/ata/libata-core.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -2057,7 +2057,7 @@ unsigned int ata_read_log_page(struct at
 
 retry:
 	ata_tf_init(dev, &tf);
-	if (dev->dma_mode && ata_id_has_read_log_dma_ext(dev->id) &&
+	if (ata_dma_enabled(dev) && ata_id_has_read_log_dma_ext(dev->id) &&
 	    !(dev->horkage & ATA_HORKAGE_NO_DMA_LOG)) {
 		tf.command = ATA_CMD_READ_LOG_DMA_EXT;
 		tf.protocol = ATA_PROT_DMA;