From: Andy Shevchenko <andriy.shevchenko@intel.com>
To: "Noralf Trønnes" <noralf@tronnes.org>
Cc: sam@ravnborg.org, david@lechnology.com, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH v2 05/11] drm/tinydrm: Remove tinydrm_spi_max_transfer_size()
Date: Tue, 15 Oct 2019 18:59:11 +0300 [thread overview]
Message-ID: <20191015155911.GM32742@smile.fi.intel.com> (raw)
In-Reply-To: <253aec49-e51c-b35b-4e7d-53a8a948655d@tronnes.org>
On Tue, Oct 15, 2019 at 05:41:53PM +0200, Noralf Trønnes wrote:
> Den 15.10.2019 16.32, skrev Andy Shevchenko:
> > On Fri, Jul 19, 2019 at 05:59:10PM +0200, Noralf Trønnes wrote:
> >> spi-bcm2835 can handle >64kB buffers now so there is no need to check
> >> ->max_dma_len. The tinydrm_spi_max_transfer_size() max_len argument is
> >> not used by any callers, so not needed.
> >>
> >> Then we have the spi_max module parameter. It was added because
> >> staging/fbtft has support for it and there was a report that someone used
> >> it to set a small buffer size to avoid popping on a USB soundcard on a
> >> Raspberry Pi. In hindsight it shouldn't have been added, I should have
> >> waited for it to become a problem first. I don't know it anyone is
> >> actually using it, but since tinydrm_spi_transfer() is being moved to
> >> mipi-dbi, I'm taking the opportunity to remove it. I'll add it back to
> >> mipi-dbi if someone complains.
> >>
> >> With that out of the way, spi_max_transfer_size() can be used instead.
> >>
> >> The chosen 16kB buffer size for Type C Option 1 (9-bit) interface is
> >> somewhat arbitrary, but a bigger buffer will have a miniscule impact on
> >> transfer speed, so it's probably fine.
> >
> > This breaks the SPI PXA2xx case I'm using. The world is not a Pi:e.
> >
> > [ 388.445752] mi0283qt spi-PRP0001:01: DMA disabled for transfer length 153600 greater than 65536
> > [ 388.634437] mi0283qt spi-PRP0001:01: DMA disabled for transfer length 153600 greater than 65536
> > [ 388.822933] mi0283qt spi-PRP0001:01: DMA disabled for transfer length 153600 greater than 65536
> >
> > The crucial thing is to check the transfer size against maximum DMA length
> > of the master.
> >
>
> Isn't this a spi controller driver problem?
It doesn't matter. This patch made a regression. Before it worked,
now it doesn't.
> spi_max_transfer_size() tells the client what the maximum transfer
> length is. The controller driver can use ctlr->max_transfer_size if it
> has restrictions.
It might be a problem of the SPI core.
> AFAIUI max_dma_len is used when splitting up the buffer for the sg table
> in spi_map_buf().
> > Please, fix.
Should I send the revert?
--
With Best Regards,
Andy Shevchenko
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
next prev parent reply other threads:[~2019-10-15 15:59 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-19 15:59 [PATCH v2 00/11] drm/tinydrm: Remove tinydrm.ko Noralf Trønnes
2019-07-19 15:59 ` [PATCH v2 01/11] drm: Add SPI connector type Noralf Trønnes
2019-07-19 15:59 ` [PATCH v2 02/11] drm/tinydrm: Use DRM_MODE_CONNECTOR_SPI Noralf Trønnes
2019-07-19 15:59 ` [PATCH v2 03/11] drm/tinydrm: Use spi_is_bpw_supported() Noralf Trønnes
2019-07-19 15:59 ` [PATCH v2 04/11] drm/tinydrm: Remove spi debug buffer dumping Noralf Trønnes
2019-07-19 15:59 ` [PATCH v2 05/11] drm/tinydrm: Remove tinydrm_spi_max_transfer_size() Noralf Trønnes
2019-10-15 14:32 ` Andy Shevchenko
2019-10-15 15:02 ` Andy Shevchenko
2019-10-15 15:41 ` Noralf Trønnes
2019-10-15 15:57 ` Daniel Vetter
2019-10-16 16:13 ` Andy Shevchenko
2019-10-16 17:44 ` Daniel Vetter
2019-10-16 18:00 ` Mark Brown
2019-10-17 6:58 ` Andy Shevchenko
2019-10-15 15:59 ` Andy Shevchenko [this message]
2019-10-15 16:05 ` Daniel Vetter
2019-10-16 8:07 ` Andy Shevchenko
2019-10-15 16:55 ` Noralf Trønnes
2019-07-19 15:59 ` [PATCH v2 06/11] drm/tinydrm: Clean up tinydrm_spi_transfer() Noralf Trønnes
2019-07-19 15:59 ` [PATCH v2 07/11] drm/tinydrm: Move tinydrm_spi_transfer() Noralf Trønnes
2019-07-19 15:59 ` [PATCH v2 08/11] drm/tinydrm: Move tinydrm_machine_little_endian() Noralf Trønnes
2019-07-19 15:59 ` [PATCH v2 09/11] drm/tinydrm/repaper: Don't use tinydrm_display_pipe_init() Noralf Trønnes
2019-07-19 15:59 ` [PATCH v2 10/11] drm/tinydrm/mipi-dbi: Add mipi_dbi_init_with_formats() Noralf Trønnes
2019-07-22 19:48 ` David Lechner
2019-07-19 15:59 ` [PATCH v2 11/11] drm/tinydrm: Move tinydrm_display_pipe_init() to mipi-dbi Noralf Trønnes
2019-07-23 14:11 ` [PATCH v2 00/11] drm/tinydrm: Remove tinydrm.ko Noralf Trønnes
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=20191015155911.GM32742@smile.fi.intel.com \
--to=andriy.shevchenko@intel.com \
--cc=david@lechnology.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=noralf@tronnes.org \
--cc=sam@ravnborg.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