From: LIU Zhiwei <zhiwei_liu@c-sky.com>
To: Alistair Francis <alistair.francis@wdc.com>
Cc: "open list:RISC-V" <qemu-riscv@nongnu.org>,
Bin Meng <bmeng.cn@gmail.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
"qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>
Subject: Re: [PATCH v5 07/11] hw/char: Initial commit of Ibex UART
Date: Tue, 2 Jun 2020 20:28:02 +0800 [thread overview]
Message-ID: <c9f16143-4e9b-a3a8-ffd3-12d43fd2e343@c-sky.com> (raw)
In-Reply-To: <cc1a1671-b926-bb31-1ed2-d2920f0faf38@c-sky.com>
Hi Alistair,
There are still some questions I don't understand.
1. Is the baud rate or fifo a necessary feature to simulate?
As you can see, qemu_chr_fe_write will send the byte as soon as possible.
When you want to transmit a byte through WDATA, you can call
qemu_chr_fe_write directly.
2. The baud rate calculation method is not strictly right.
I think when a byte write to FIFO, char_tx_time * 8 is the correct time
to send the byte instead of
char_tx_time * 4.
3. Why add a watch here?
> + s->uart_status |= UART_STATUS_TXEMPTY;
> + s->uart_intr_state |= INTR_STATE_TX_EMPTY;
> + s->uart_intr_state &= ~INTR_STATE_TX_WATERMARK;
> + ibex_uart_update_irqs(s);
> + return FALSE;
> + }
> +
> + ret = qemu_chr_fe_write(&s->chr, s->tx_fifo, s->tx_level);
> +
> + if (ret >= 0) {
> + s->tx_level -= ret;
> + memmove(s->tx_fifo, s->tx_fifo + ret, s->tx_level);
> + }
> +
> + if (s->tx_level) {
> + guint r = qemu_chr_fe_add_watch(&s->chr, G_IO_OUT | G_IO_HUP,
> + ibex_uart_xmit, s);
> + if (!r) {
> + s->tx_level = 0;
> + return FALSE;
> + }
> + }
> +
Zhiwei
next prev parent reply other threads:[~2020-06-02 12:29 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-28 22:14 [PATCH v5 00/11] RISC-V Add the OpenTitan Machine Alistair Francis
2020-05-28 22:14 ` [PATCH v5 01/11] riscv/boot: Add a missing header include Alistair Francis
2020-05-28 22:14 ` [PATCH v5 02/11] target/riscv: Don't overwrite the reset vector Alistair Francis
2020-05-28 22:14 ` [PATCH v5 03/11] target/riscv: Disable the MMU correctly Alistair Francis
2020-06-01 5:24 ` Bin Meng
2020-05-28 22:14 ` [PATCH v5 04/11] target/riscv: Don't set PMP feature in the cpu init Alistair Francis
2020-06-01 5:26 ` Bin Meng
2020-05-28 22:14 ` [PATCH v5 05/11] target/riscv: Add the lowRISC Ibex CPU Alistair Francis
2020-05-28 22:14 ` [PATCH v5 06/11] riscv: Initial commit of OpenTitan machine Alistair Francis
2020-06-09 13:48 ` Damien Hedde
2020-06-09 14:21 ` Philippe Mathieu-Daudé
2020-06-09 23:09 ` Alistair Francis
2020-09-08 14:52 ` Peter Maydell
2020-09-09 17:49 ` Alistair Francis
2020-09-09 19:00 ` Peter Maydell
2020-09-09 19:51 ` Palmer Dabbelt
2020-09-10 18:48 ` Alistair Francis
2023-05-19 17:15 ` [PATCH v5 6/11] " Philippe Mathieu-Daudé
2020-05-28 22:14 ` [PATCH v5 07/11] hw/char: Initial commit of Ibex UART Alistair Francis
2020-06-01 21:23 ` Alistair Francis
2020-06-02 11:22 ` LIU Zhiwei
2020-06-02 12:28 ` LIU Zhiwei [this message]
2020-06-02 17:54 ` Alistair Francis
2020-06-03 10:33 ` LIU Zhiwei
2020-06-03 15:56 ` Alistair Francis
2020-06-04 1:59 ` LIU Zhiwei
2020-06-04 4:35 ` Alistair Francis
2020-06-04 5:05 ` LIU Zhiwei
2020-06-04 5:46 ` Alistair Francis
2020-06-04 5:40 ` LIU Zhiwei
2020-06-02 17:46 ` Alistair Francis
2020-05-28 22:14 ` [PATCH v5 08/11] hw/intc: Initial commit of lowRISC Ibex PLIC Alistair Francis
2020-05-28 22:14 ` [PATCH v5 09/11] riscv/opentitan: Connect the PLIC device Alistair Francis
2020-05-28 22:14 ` [PATCH v5 10/11] riscv/opentitan: Connect the UART device Alistair Francis
2020-05-28 22:14 ` [PATCH v5 11/11] target/riscv: Use a smaller guess size for no-MMU PMP Alistair Francis
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=c9f16143-4e9b-a3a8-ffd3-12d43fd2e343@c-sky.com \
--to=zhiwei_liu@c-sky.com \
--cc=alistair.francis@wdc.com \
--cc=bmeng.cn@gmail.com \
--cc=palmer@dabbelt.com \
--cc=qemu-devel@nongnu.org \
--cc=qemu-riscv@nongnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).