[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: [PATCH 2/3] xen/arm: vpl011: Handle correctly TXFE when backend in Xen
- To: Michal Orzel <michal.orzel@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
- From: Henry Wang <Henry.Wang@xxxxxxx>
- Date: Wed, 12 Apr 2023 07:17:45 +0000
- Accept-language: zh-CN, en-US
- Arc-authentication-results: i=1; mx.microsoft.com 1; spf=pass smtp.mailfrom=arm.com; dmarc=pass action=none header.from=arm.com; dkim=pass header.d=arm.com; arc=none
- Arc-message-signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=microsoft.com; s=arcselector9901; h=From:Date:Subject:Message-ID:Content-Type:MIME-Version:X-MS-Exchange-AntiSpam-MessageData-ChunkCount:X-MS-Exchange-AntiSpam-MessageData-0:X-MS-Exchange-AntiSpam-MessageData-1; bh=8Fnve0Ztn4Wjfr4f/V2rjsT2NHcKUk9HKR+bwZFLvtc=; b=EfCwq65pgHkLjORH9b+qT3uYCSFr34Z5cjX/cHJMAKSxq8f2e+2vqUsPyP3Ol33vYrHepexNNOG6tKcaL7mJf9932RsBQbof6JGtlIfVso2/08ojBBCUlCb6oqOHMhy3FgMxUv3S5IYBeMPSlUsUO+c11d1iMDHS82mda5cWGHJ+RsJAQ7PNBiPxBKU2v4QgodAdQ178yXrvVkeYOo5j//8/Hxj33ikGv3ED7JBY+sSpk8wAP4oD7pjrFDANzVdoqaQWVDPPYRBlIxYR0+nkCcy99tGTB6bYHMhbnHjIEfEdDyZVgFhiTe0FCd6XTLD3oYsWb7q73x4Fucv99QzIYg==
- Arc-seal: i=1; a=rsa-sha256; s=arcselector9901; d=microsoft.com; cv=none; b=J1crUVwBDPTW1NvxRDV5eMksN6QeaD8uO3cmHDY0LWsYuCRlUflwn0Yu/jYpyqED2+9E/OQaqtA+cgHOVy7VE4gSTRKTkWjagZPzoeVqIhAgiMyy3VR4cyl4k69DWW0cblcsvbiF+mX2JrmYk+xgZv4AXMBx62DRt/HCRTTbPruC1C2iXHgu6g/LRWXKkSf5AzzSafkTSShH10hpziOU+7flaRW+1CcFbnMp6nPqD8y+W+7ne6cGD6EJyYc07AcUa3kALETaMXjAvnQOLdUAeVxSNgSvDSNEe5FNdj3XXYlqnDk0GjAjZeqa83bJNaK1A3VeO9I5B+T9eew16DVykQ==
- Authentication-results-original: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=arm.com;
- Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, Volodymyr Babchuk <Volodymyr_Babchuk@xxxxxxxx>
- Delivery-date: Wed, 12 Apr 2023 07:18:18 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
- Nodisclaimer: true
- Original-authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=arm.com;
- Thread-index: AQHZZ7BjfTPA7ZSpsEidFkEBoEBCAa8nPfIg
- Thread-topic: [PATCH 2/3] xen/arm: vpl011: Handle correctly TXFE when backend in Xen
Hi Michal,
> -----Original Message-----
> Subject: [PATCH 2/3] xen/arm: vpl011: Handle correctly TXFE when backend in
> Xen
>
> When backend is in Xen, the handling of data written to DR register is a
> bit special because we want to tell guest that we are always ready for new
> data to be written (i.e. no real FIFO, TXFF/BUSY never set and TXI always
> set). This conflicts with the current handling of TXFE bit, which we
> always clear and never set on a write path (we happen to set it when we
> receive char from serial input due to use of vpl011_data_avail() but this
> might never be called). This can lead to issues if a guest driver makes
> use of TXFE bit to check for TX transmission completion (such guest could
> then wait endlessly). Fix it by keeping TXFE always set to match the
> current emulation logic.
>
> Signed-off-by: Michal Orzel <michal.orzel@xxxxxxx>
Reviewed-by: Henry Wang <Henry.Wang@xxxxxxx>
Tested-by: Henry Wang <Henry.Wang@xxxxxxx>
Kind regards,
Henry
|
