From: Geert Uytterhoeven <geert@linux-m68k.org>
To: John Garry <john.garry@huawei.com>
Cc: Mark Brown <broonie@kernel.org>,
linux-spi <linux-spi@vger.kernel.org>,
Linuxarm <linuxarm@huawei.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
MTD Maling List <linux-mtd@lists.infradead.org>,
Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Subject: Re: [PATCH RFC 1/3] spi: Allow SPI controller override device buswidth
Date: Mon, 2 Mar 2020 17:12:05 +0100 [thread overview]
Message-ID: <CAMuHMdV9v-7eRqi3JjcNaOBpRrC2-gLDCizYOJwhQCjZiLr5dA@mail.gmail.com> (raw)
In-Reply-To: <1582903131-160033-2-git-send-email-john.garry@huawei.com>
Hi John,
Thanks for your patch!
On Fri, Feb 28, 2020 at 4:23 PM John Garry <john.garry@huawei.com> wrote:
> Currently ACPI firmware description for a SPI device does not have any
> method to describe the data buswidth on the board.
>
> So even through the controller and device may support higher modes than
> standard SPI, it cannot be assumed that the board does - as such, that
> device is limited to standard SPI in such a circumstance.
Indeed.
> As a workaround, allow the controller driver supply buswidth override bits,
> which are used inform the core code that the controller driver knows the
> buswidth supported on that board for that device.
I feel this is a bit dangerous, and might bite us one day.
> A host controller driver might know this info from DMI tables, for example.
Can't acpi_register_spi_device() obtain that info from DMI tables,
to avoid contaminating the generic code?
> Signed-off-by: John Garry <john.garry@huawei.com>
> --- a/drivers/spi/spi.c
> +++ b/drivers/spi/spi.c
> @@ -510,6 +510,7 @@ struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
> spi->dev.bus = &spi_bus_type;
> spi->dev.release = spidev_release;
> spi->cs_gpio = -ENOENT;
> + spi->mode = ctlr->buswidth_override_bits;
This could just be moved to acpi_register_spi_device(), right?
>
> spin_lock_init(&spi->statistics.lock);
>
> @@ -2181,9 +2182,10 @@ static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
> return AE_NO_MEMORY;
> }
>
> +
> ACPI_COMPANION_SET(&spi->dev, adev);
> spi->max_speed_hz = lookup.max_speed_hz;
> - spi->mode = lookup.mode;
> + spi->mode |= lookup.mode;
> spi->irq = lookup.irq;
> spi->bits_per_word = lookup.bits_per_word;
> spi->chip_select = lookup.chip_select;
> diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
> index 6d16ba01ff5a..600e3793303e 100644
> --- a/include/linux/spi/spi.h
> +++ b/include/linux/spi/spi.h
> @@ -481,6 +481,9 @@ struct spi_controller {
> /* spi_device.mode flags understood by this controller driver */
> u32 mode_bits;
>
> + /* spi_device.mode flags override flags for this controller */
> + u32 buswidth_override_bits;
And I'd be happy if we could avoid adding this here ;-)
> +
> /* bitmask of supported bits_per_word for transfers */
> u32 bits_per_word_mask;
> #define SPI_BPW_MASK(bits) BIT((bits) - 1)
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2020-03-02 16:12 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-28 15:18 [PATCH RFC 0/3] spi/HiSilicon v3xx: Support dual and quad mode through DMI quirks John Garry
2020-02-28 15:18 ` [PATCH RFC 1/3] spi: Allow SPI controller override device buswidth John Garry
2020-03-02 16:12 ` Geert Uytterhoeven [this message]
2020-03-02 16:33 ` Mark Brown
[not found] ` <1582903131-160033-2-git-send-email-john.garry-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2020-02-28 18:25 ` Applied "spi: Allow SPI controller override device buswidth" to the spi tree Mark Brown
2020-03-01 10:04 ` [PATCH RFC 1/3] spi: Allow SPI controller override device buswidth Sergei Shtylyov
2020-03-02 9:30 ` John Garry
[not found] ` <07bb2213-5543-0ef0-9585-be83026c1199-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2020-03-02 12:22 ` Mark Brown
2020-03-02 18:51 ` Geert Uytterhoeven
[not found] ` <CAMuHMdW7Xu6EzfmVFx1+i1byy3KOS5A+h2GuMb8nkZ+-jD1=BA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2020-03-03 9:42 ` John Garry
[not found] ` <f6f21e75-7cee-89da-bb87-95327a4ec2cc-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2020-03-03 12:43 ` Mark Brown
[not found] ` <1582903131-160033-1-git-send-email-john.garry-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2020-02-28 15:18 ` [PATCH RFC 2/3] spi: HiSilicon v3xx: Properly set CMD_CONFIG for Dual/Quad modes John Garry
[not found] ` <1582903131-160033-3-git-send-email-john.garry-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2020-02-28 18:25 ` Applied "spi: HiSilicon v3xx: Properly set CMD_CONFIG for Dual/Quad modes" to the spi tree Mark Brown
2020-02-28 15:18 ` [PATCH RFC 3/3] spi: HiSilicon v3xx: Use DMI quirk to set controller buswidth override bits John Garry
[not found] ` <1582903131-160033-4-git-send-email-john.garry-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>
2020-02-28 16:20 ` Mark Brown
[not found] ` <20200228162057.GC4956-GFdadSzt00ze9xe1eoZjHA@public.gmane.org>
2020-02-28 17:17 ` John Garry
2020-02-28 18:25 ` Applied "spi: HiSilicon v3xx: Use DMI quirk to set controller buswidth override bits" to the spi tree Mark Brown
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=CAMuHMdV9v-7eRqi3JjcNaOBpRrC2-gLDCizYOJwhQCjZiLr5dA@mail.gmail.com \
--to=geert@linux-m68k.org \
--cc=andriy.shevchenko@linux.intel.com \
--cc=broonie@kernel.org \
--cc=john.garry@huawei.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mtd@lists.infradead.org \
--cc=linux-spi@vger.kernel.org \
--cc=linuxarm@huawei.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).