linux-kernel - [PATCH v3] usb: musb: remove unused variable 'devctl'

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Message-ID: <20201124084955.30270-1-min.guo@mediatek.com>
Date:   Tue, 24 Nov 2020 16:49:55 +0800
From:   <min.guo@...iatek.com>
To:     Bin Liu <b-liu@...com>
CC:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Matthias Brugger <matthias.bgg@...il.com>,
        <chunfeng.yun@...iatek.com>, <linux-usb@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-mediatek@...ts.infradead.org>,
        Min Guo <min.guo@...iatek.com>
Subject: [PATCH v3] usb: musb: remove unused variable 'devctl'

From: Min Guo <min.guo@...iatek.com>

Remove unused 'devctl' variable to fix compile warnings:

    drivers/usb/musb/musbhsdma.c: In function 'dma_controller_irq':
    drivers/usb/musb/musbhsdma.c:324:8: warning: variable 'devctl' set
    but not used [-Wunused-but-set-variable]

Signed-off-by: Min Guo <min.guo@...iatek.com>
---
changes in v3
suggested by Greg Kroah-Hartman:
Add a comment.

changes in v2
suggested by Alan Stern:
Add void before musb_read to indicate that the register MUSB_DEVCTL
was intended to be read and discarded.
---
 drivers/usb/musb/musbhsdma.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/musb/musbhsdma.c b/drivers/usb/musb/musbhsdma.c
index 0aacfc8be5a1..2a345b4ad015 100644
--- a/drivers/usb/musb/musbhsdma.c
+++ b/drivers/usb/musb/musbhsdma.c
@@ -321,8 +321,6 @@ irqreturn_t dma_controller_irq(int irq, void *private_data)
 				musb_channel->channel.status =
 					MUSB_DMA_STATUS_BUS_ABORT;
 			} else {
-				u8 devctl;
-
 				addr = musb_read_hsdma_addr(mbase,
 						bchannel);
 				channel->actual_len = addr
@@ -336,7 +334,11 @@ irqreturn_t dma_controller_irq(int irq, void *private_data)
 						< musb_channel->len) ?
 					"=> reconfig 0" : "=> complete");
 
-				devctl = musb_readb(mbase, MUSB_DEVCTL);
+				/*
+				 * Some hardware may need to read the
+				 * MUSB_DEVCTL register once to take effect.
+				 */
+				(void)musb_readb(mbase, MUSB_DEVCTL);
 
 				channel->status = MUSB_DMA_STATUS_FREE;
 
-- 
2.18.0