From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.1 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,HTML_MESSAGE,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C832C433E0 for ; Tue, 9 Mar 2021 15:59:04 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EEBCA6522D for ; Tue, 9 Mar 2021 15:59:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EEBCA6522D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ulal.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([::1]:39712 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1lJelC-0002fc-Tz for qemu-devel@archiver.kernel.org; Tue, 09 Mar 2021 10:59:02 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:59782) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lJeOV-0008LR-Rd for qemu-devel@nongnu.org; Tue, 09 Mar 2021 10:35:36 -0500 Received: from mo4-p01-ob.smtp.rzone.de ([81.169.146.166]:30749) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1lJeOS-0002AV-VY for qemu-devel@nongnu.org; Tue, 09 Mar 2021 10:35:35 -0500 ARC-Seal: i=1; a=rsa-sha256; t=1615304124; cv=none; d=strato.com; s=strato-dkim-0002; b=r1uoUt4dgk/RB3lIdbIaOoWxsR1toAY5zRpbcy+bEQFjWbo6dH3yW8OZVKGmLjJrbO cdISTljoL0EYz7o4IYJR5RNG2Gzxi2NYXEtRxH3QsO5qEZFQYiJFHo9FwutNKS0aRPlJ BMVBl+IO9jLSPGLYZ4Y8JVi/rqKB9WOmpiuClmLAzou+7KRWz/hLhlSETkxdDk9h0uhb xG7wV2YO3P+fuNbfL1b3cnsX6IRtbtsaoREbVlY0D9k8OCd2p3ymlqW5j6IU7XgjkbVl GZFWKr9SuQkrVDYFq51qeIvsJ71lC0jl/w9UxQXzo+3kC2ACpxa4/VZGtWhJpWG7B2kb HOHQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; t=1615304124; s=strato-dkim-0002; d=strato.com; h=In-Reply-To:Date:Message-ID:From:References:Cc:To:Subject:Cc:Date: From:Subject:Sender; bh=RqOiIrXVJZiBq4p3O3z/tQfVLJvgSlFsbpVX3hMtdKg=; b=U25T5L5emqjavgN4AqlTvYt7eDSvdNpcxq5OWJIHtWY//Vi7F+WJFXHIIIWtwz2Uor RsGa/rfu41naFdHjZ8d9bCklaHTc6XQQ13+X8u+ILgja8bDv2dKt4QVSTwuW3BIUcnuP 8x50GpKhYPr/yRiJ/4UDBCBcKLCrT4cRd8MH4nuB+J6KyIwJKN5y5jlh86twvCKb/l0A 97mr0cXYl5NxonVGbf3Wy5FkwDgQ0zyqOAXTfGLhUd9iZvy6xOOB3P4s0tzoeKFcnYVd Z7ETtHtSjZ9erVN1FMp3sM8RvtZ1JnlhUOhrjx+xmUNmybopiDTPuC83hdYe/iURGL3p V1xg== ARC-Authentication-Results: i=1; strato.com; dkim=none DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1615304124; s=strato-dkim-0002; d=ulal.de; h=In-Reply-To:Date:Message-ID:From:References:Cc:To:Subject:Cc:Date: From:Subject:Sender; bh=RqOiIrXVJZiBq4p3O3z/tQfVLJvgSlFsbpVX3hMtdKg=; b=FZTdJDGi7TOqaTmOMkyMLw9vdcB5PvsE23JGbBJJQBEwphr73W6C49ByVT/6UbmTtS kvWQ1hC58AGfyB1MFEvCxp9tYQBmC/dogaYR9jv9W6teCzRLpWXDhOcZ3WP5/uOtW1Ts HHymf89VnHM8yF8K29WxYEdRxrY9X7fV/vVlOgSTvNU8lUTjZiZEqGyZ2PagIIe8tuPJ dH1izai9FapGigdCsH63ZtYPo4RGV4mmFlIjJdfvKArmuHw0vd4OUBE0+vxNzJ8TAh24 +fv6bwPPF9RF6SlAwK8hVNHihXT6AP7EjaJ2yFRZewTpr462z7SWd3gFmc4aNUmqWJFd friA== Authentication-Results: strato.com; dkim=none X-RZG-AUTH: ":LWABbUGmf/p3d3fx281mbpk9zOkHG9L8L9MnY9md4b2JSSHyzkN3ON0Uun6F+zrkVqc/ZmTClqkOE9IdMVvnQ2O6vlW7Z+qlJRBbUq68WzKpoQ==" X-RZG-CLASS-ID: mo00 Received: from [IPv6:2003:c3:9719:3d00:bb52:98ae:ee53:17cd] by smtp.strato.de (RZmta 47.20.3 AUTH) with ESMTPSA id c075a1x29FZNHmz (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256 bits)) (Client did not present a certificate); Tue, 9 Mar 2021 16:35:23 +0100 (CET) Subject: Re: [PATCH] hw/char: disable ibex uart receive if the buffer is full To: Alistair Francis References: <20210215231528.2718086-1-alexander.wagner@ulal.de> <19c50d64-fe9d-8c72-2002-3586abac821c@ulal.de> From: Alexander Wagner Message-ID: <0f1e36fb-6ac4-b709-a9ba-2754e3f1fe78@ulal.de> Date: Tue, 9 Mar 2021 16:35:23 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/alternative; boundary="------------9D5936DC0AA7FBA8D2BFAF6B" Content-Language: en-US Received-SPF: none client-ip=81.169.146.166; envelope-from=alexander.wagner@ulal.de; helo=mo4-p01-ob.smtp.rzone.de X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, HTML_MESSAGE=0.001, NICE_REPLY_A=-0.001, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_PASS=-0.001, SPF_NONE=0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?Q?Marc-Andr=c3=a9_Lureau?= , Alistair Francis , "qemu-devel@nongnu.org Developers" , Paolo Bonzini Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is a multi-part message in MIME format. --------------9D5936DC0AA7FBA8D2BFAF6B Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit On 09.03.21 15:29, Alistair Francis wrote: > On Tue, Mar 9, 2021 at 2:27 AM Alexander Wagner > wrote: >> >> On 08.03.21 14:47, Alistair Francis wrote: >>>> hw/char/ibex_uart.c | 20 +++++++++++++++----- >>>> include/hw/char/ibex_uart.h | 4 ++++ >>>> 2 files changed, 19 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/hw/char/ibex_uart.c b/hw/char/ibex_uart.c >>>> index 89f1182c9b..dac09d53d6 100644 >>>> --- a/hw/char/ibex_uart.c >>>> +++ b/hw/char/ibex_uart.c >>>> @@ -66,7 +66,8 @@ static int ibex_uart_can_receive(void *opaque) >>>> { >>>> IbexUartState *s = opaque; >>>> >>>> - if (s->uart_ctrl & R_CTRL_RX_ENABLE_MASK) { >>>> + if ((s->uart_ctrl & R_CTRL_RX_ENABLE_MASK) >>>> + && !(s->uart_status & R_STATUS_RXFULL_MASK)) { >>>> return 1; >>>> } >>>> >>>> @@ -83,6 +84,8 @@ static void ibex_uart_receive(void *opaque, const uint8_t *buf, int size) >>>> >>>> s->uart_status &= ~R_STATUS_RXIDLE_MASK; >>>> s->uart_status &= ~R_STATUS_RXEMPTY_MASK; >>>> + s->uart_status |= R_STATUS_RXFULL_MASK; >>> Doesn't this mean we set RXFULL on every receive? Shouldn't this check >>> the rx_level first? >>> >>> Alistair >> Thank you for having a look! :) >> >> Yes, this is correct. The RXFULL is currently set on every receive. The >> RXFULL is used to indicate to QEMU that the device cannot receive any >> further bytes. >> >> As the FIFO buffers are currently not yet implemented I thought it would >> make sense to behave like the OT UART could only receive one byte at a time. > Ah, good point. > > Can you add a comment where it is set describing that then? > > Alistair > Sure, I just added a comment and emailed this as patch v2. Alex --------------9D5936DC0AA7FBA8D2BFAF6B Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 7bit


On 09.03.21 15:29, Alistair Francis wrote:
On Tue, Mar 9, 2021 at 2:27 AM Alexander Wagner
<alexander.wagner@ulal.de> wrote:


On 08.03.21 14:47, Alistair Francis wrote:

  hw/char/ibex_uart.c         | 20 +++++++++++++++-----
  include/hw/char/ibex_uart.h |  4 ++++
  2 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/hw/char/ibex_uart.c b/hw/char/ibex_uart.c
index 89f1182c9b..dac09d53d6 100644
--- a/hw/char/ibex_uart.c
+++ b/hw/char/ibex_uart.c
@@ -66,7 +66,8 @@ static int ibex_uart_can_receive(void *opaque)
  {
      IbexUartState *s = opaque;

-    if (s->uart_ctrl & R_CTRL_RX_ENABLE_MASK) {
+    if ((s->uart_ctrl & R_CTRL_RX_ENABLE_MASK)
+           && !(s->uart_status & R_STATUS_RXFULL_MASK)) {
          return 1;
      }

@@ -83,6 +84,8 @@ static void ibex_uart_receive(void *opaque, const uint8_t *buf, int size)

      s->uart_status &= ~R_STATUS_RXIDLE_MASK;
      s->uart_status &= ~R_STATUS_RXEMPTY_MASK;
+    s->uart_status |= R_STATUS_RXFULL_MASK;

Doesn't this mean we set RXFULL on every receive? Shouldn't this check
the rx_level first?

Alistair

Thank you for having a look! :)

Yes, this is correct. The RXFULL is currently set on every receive. The
RXFULL is used to indicate to QEMU that the device cannot receive any
further bytes.

As the FIFO buffers are currently not yet implemented I thought it would
make sense to behave like the OT UART could only receive one byte at a time.

Ah, good point.

Can you add a comment where it is set describing that then?

Alistair


Sure, I just added a comment and emailed this as patch v2.

Alex
--------------9D5936DC0AA7FBA8D2BFAF6B--