From: Wolfram Sang <wsa@the-dreams.de>
To: Ulrich Hecht <uli+renesas@fpond.eu>
Cc: linux-renesas-soc@vger.kernel.org, geert@linux-m68k.org,
linux-i2c@vger.kernel.org,
Geert Uytterhoeven <geert+renesas@glider.be>
Subject: Re: [PATCH v4] i2c: sh_mobile: implement atomic transfers
Date: Fri, 2 Oct 2020 17:44:23 +0200 [thread overview]
Message-ID: <20201002154423.GA16758@ninjato> (raw)
In-Reply-To: <20200928155950.1185-1-uli+renesas@fpond.eu>
[-- Attachment #1: Type: text/plain, Size: 1825 bytes --]
Hi Uli,
On Mon, Sep 28, 2020 at 05:59:50PM +0200, Ulrich Hecht wrote:
> Implements atomic transfers to fix reboot/shutdown on r8a7790 Lager and
> similar boards.
>
> Signed-off-by: Ulrich Hecht <uli+renesas@fpond.eu>
> Tested-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
It works, but I have two comments and two questions:
> @@ -581,10 +585,12 @@ static void start_ch(struct sh_mobile_i2c_data *pd, struct i2c_msg *usr_msg,
> pd->pos = -1;
> pd->sr = 0;
>
> + if (pd->atomic_xfer)
> + return;
> +
> pd->dma_buf = i2c_get_dma_safe_msg_buf(pd->msg, 8);
> if (pd->dma_buf)
> sh_mobile_i2c_xfer_dma(pd);
> -
This blank line should stay.
...
> + if (pd->atomic_xfer) {
> + unsigned long j = jiffies + pd->adap.timeout;
> +
> + time_left = time_before_eq(jiffies, j);
> + while (time_left &&
> + !(pd->sr & (ICSR_TACK | SW_DONE))) {
> + unsigned char sr = iic_rd(pd, ICSR);
> +
> + if (sr & (ICSR_AL | ICSR_TACK |
> + ICSR_WAIT | ICSR_DTE)) {
> + sh_mobile_i2c_isr(0, pd);
> + udelay(150);
> + } else {
> + cpu_relax();
> + }
Is it 100% safe to call cpu_relax() that late? Aren't interrupts
disabled? What is waking the CPU again? And where does the value 150us
come from?
> + time_left = time_before_eq(jiffies, j);
> + }
> + } else {
> + /* The interrupt handler takes care of the rest... */
> + time_left = wait_event_timeout(pd->wait,
> + pd->sr & (ICSR_TACK | SW_DONE),
> + pd->adap.timeout);
> +
> + /* 'stop_after_dma' tells if DMA xfer was complete */
> + i2c_put_dma_safe_msg_buf(pd->dma_buf, pd->msg,
> + pd->stop_after_dma);
>
This blank line can go.
Thanks and regards,
Wolfram
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
next prev parent reply other threads:[~2020-10-02 15:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-28 15:59 [PATCH v4] i2c: sh_mobile: implement atomic transfers Ulrich Hecht
2020-10-02 15:44 ` Wolfram Sang [this message]
2020-10-05 7:36 ` Geert Uytterhoeven
2020-10-06 7:59 ` Ulrich Hecht
2020-10-05 7:39 ` Geert Uytterhoeven
2020-10-06 6:40 ` Wolfram Sang
2020-10-08 9:48 ` Wolfram Sang
2020-11-06 14:27 ` Wolfram Sang
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=20201002154423.GA16758@ninjato \
--to=wsa@the-dreams.de \
--cc=geert+renesas@glider.be \
--cc=geert@linux-m68k.org \
--cc=linux-i2c@vger.kernel.org \
--cc=linux-renesas-soc@vger.kernel.org \
--cc=uli+renesas@fpond.eu \
/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).