From: hammer hsieh <hammerh0314@gmail.com>
To: Jiri Slaby <jirislaby@kernel.org>
Cc: Greg KH <gregkh@linuxfoundation.org>,
robh+dt@kernel.org, linux-serial@vger.kernel.org,
devicetree@vger.kernel.org, linux-kernel@vger.kernel.org,
p.zabel@pengutronix.de, wells.lu@sunplus.com,
"hammer.hsieh" <hammer.hsieh@sunplus.com>
Subject: Re: [PATCH v6 2/2] serial:sunplus-uart:Add Sunplus SoC UART Driver
Date: Fri, 14 Jan 2022 10:22:56 +0800 [thread overview]
Message-ID: <CAOX-t573QkixRC7xa1KUOYXfL12Q+Ltxph9rX7V8tm2BMoqxgA@mail.gmail.com> (raw)
In-Reply-To: <2cde3ff0-5180-7c1e-82fd-7b58e41d462a@kernel.org>
Jiri Slaby <jirislaby@kernel.org> 於 2022年1月13日 週四 下午7:12寫道：
>
> On 13. 01. 22, 11:56, hammer hsieh wrote:
> >> Could you explain me what posted write is and how does it not matter in
> >> this case?
> >>
> >
> > Each UART ISC register contains
>
> No, you still don't follow what I write. Use your favorite web search
> for "posted write" and/or consult with your HW team.
>
Maybe this time, we are on the same page.
Our SP7021 chipset is designed on ARM Cortex-A7 Quad core.
Register Access through AMBA(AXI bus), and it is non-cached.
Did you mean
case1 have concern about "posted write", and you want to know why it not matter?
case2 will be safer?
Case1 :
spin_lock_irq_save()
writel(0, target register)
spin_unlock_irqrestore()
Case2 :
spin_lock_irq_save()
tmp = readl(target register)
tmp &= ~(bit4 | bit5)
writel(tmp, target register)
spin_unlock_irqrestore()
I test uart port with linux-serial-test tool.
Ex. send char
linux-serial-test -y 0x55 -z 0x31 -p /dev/ttySUPx -b 115200
driver will call from uart startup till uart shutdown.
And it works fine, so I didn't think about "posted write" on Register bus.
> --
> js
> suse labs
next prev parent reply other threads:[~2022-01-14 2:22 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-12 9:24 [PATCH v6 0/2] Add UART driver for Suplus SP7021 SoC Hammer Hsieh
2022-01-12 9:24 ` [PATCH v6 1/2] dt-bindings:serial:Add bindings doc for Sunplus SoC UART Driver Hammer Hsieh
2022-01-12 9:24 ` [PATCH v6 2/2] serial:sunplus-uart:Add " Hammer Hsieh
2022-01-13 7:06 ` Jiri Slaby
2022-01-13 8:54 ` hammer hsieh
2022-01-13 9:08 ` Jiri Slaby
2022-01-13 10:56 ` hammer hsieh
2022-01-13 11:12 ` Jiri Slaby
2022-01-14 2:22 ` hammer hsieh [this message]
2022-01-26 13:47 ` Greg KH
2022-01-28 3:36 ` hammer hsieh
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=CAOX-t573QkixRC7xa1KUOYXfL12Q+Ltxph9rX7V8tm2BMoqxgA@mail.gmail.com \
--to=hammerh0314@gmail.com \
--cc=devicetree@vger.kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=hammer.hsieh@sunplus.com \
--cc=jirislaby@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-serial@vger.kernel.org \
--cc=p.zabel@pengutronix.de \
--cc=robh+dt@kernel.org \
--cc=wells.lu@sunplus.com \
/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).