From b4637ed6cd5375f04ac51d6b900a9ccad6c6c03a Mon Sep 17 00:00:00 2001 From: Jeff Kubascik Date: Mon, 25 Nov 2019 15:58:00 -0500 Subject: [PATCH] xen/arm: initialize vpl011 flag register The tx/rx fifo flags were not set when the vpl011 is initialized. This is a problem for certain guests that are operating in polled mode, as a guest will generally check the rx fifo empty flag to determine if there is data before doing a read. The result is a continuous spam of the message "vpl011: Unexpected IN ring buffer empty" before the first valid character is received. This initializes the flag status register to the default specified in the PL011 technical reference manual. Signed-off-by: Jeff Kubascik Acked-by: Julien Grall --- xen/arch/arm/vpl011.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/xen/arch/arm/vpl011.c b/xen/arch/arm/vpl011.c index 7bc5eeb207..895f436cc4 100644 --- a/xen/arch/arm/vpl011.c +++ b/xen/arch/arm/vpl011.c @@ -668,6 +668,8 @@ int domain_vpl011_init(struct domain *d, struct vpl011_init_info *info) goto out2; } + vpl011->uartfr = TXFE | RXFE; + spin_lock_init(&vpl011->lock); register_mmio_handler(d, &vpl011_mmio_handler, -- 2.30.2