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usbnet: smsc95xx: Don't clear read-only PHY interrupt

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[ Upstream commit 3108871f19221372b251f7da1ac38736928b5b3a ]

Upon receiving data from the Interrupt Endpoint, the SMSC LAN95xx driver
attempts to clear the signaled interrupts by writing "all ones" to the
Interrupt Status Register.

However the driver only ever enables a single type of interrupt, namely
the PHY Interrupt.  And according to page 119 of the LAN950x datasheet,
its bit in the Interrupt Status Register is read-only.  There's no other
way to clear it than in a separate PHY register:

https://www.microchip.com/content/dam/mchp/documents/UNG/ProductDocuments/DataSheets/LAN950x-Data-Sheet-DS00001875D.pdf

Consequently, writing "all ones" to the Interrupt Status Register is
pointless and can be dropped.

Tested-by: Oleksij Rempel <o.rempel@pengutronix.de> # LAN9514/9512/9500
Tested-by: Ferry Toth <fntoth@gmail.com> # LAN9514
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Lukas Wunner 2022-05-12 10:42:02 +02:00 committed by Greg Kroah-Hartman
parent c232db6727
commit 0488724388
1 changed files with 0 additions and 4 deletions
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4
drivers/net/usb/smsc95xx.c
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@ -570,10 +570,6 @@ static int smsc95xx_link_reset(struct usbnet *dev)
unsigned long flags;
int ret;
ret = smsc95xx_write_reg(dev, INT_STS, INT_STS_CLEAR_ALL_);
if (ret < 0)
return ret;
spin_lock_irqsave(&pdata->mac_cr_lock, flags);
if (pdata->phydev->duplex != DUPLEX_FULL) {
pdata->mac_cr &= ~MAC_CR_FDPX_;