From f1be0b62a03b90a40a03e21f965e4cbb89809bb1 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?= Date: Tue, 7 Jun 2022 14:07:34 +0200 Subject: [PATCH 20/51] ns16550: use poll mode if INTERRUPT_LINE is 0xff MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Intel LPSS has INTERRUPT_LINE set to 0xff by default, that is declared by the PCI Local Bus Specification Revision 3.0 (from 2004) as "unknown"/"no connection". Fallback to poll mode in this case. The 0xff handling is x86-specific, the surrounding code is guarded with CONFIG_X86 anyway. Signed-off-by: Marek Marczykowski-Górecki Reviewed-by: Roger Pau Monné master commit: 6a2ea1a2370a0c8a0210accac0ae62e68c185134 master date: 2022-05-20 12:19:45 +0200 --- xen/drivers/char/ns16550.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/xen/drivers/char/ns16550.c b/xen/drivers/char/ns16550.c index 30596d60d4ed..2d2bd2a02469 100644 --- a/xen/drivers/char/ns16550.c +++ b/xen/drivers/char/ns16550.c @@ -1221,6 +1221,19 @@ pci_uart_config(struct ns16550 *uart, bool_t skip_amt, unsigned int idx) pci_conf_read8(PCI_SBDF(0, b, d, f), PCI_INTERRUPT_LINE) : 0; +#ifdef CONFIG_X86 + /* + * PCI Local Bus Specification Revision 3.0 defines 0xff value + * as special only for X86. + */ + if ( uart->irq == 0xff ) + uart->irq = 0; +#endif + if ( !uart->irq ) + printk(XENLOG_INFO + "ns16550: %pp: no legacy IRQ, using poll mode\n", + &PCI_SBDF(0, b, d, f)); + return 0; } } -- 2.35.1