All of lore.kernel.org
 help / color / mirror / Atom feed
From: Boris Brezillon <boris.brezillon@collabora.com>
To: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Cc: Dirk Behme <dirk.behme@de.bosch.com>,
	Vignesh Raghavendra <vigneshr@ti.com>,
	Richard Weinberger <richard@nod.at>,
	Mark Brown <broonie@kernel.org>,
	linux-mtd@lists.infradead.org,
	Miquel Raynal <miquel.raynal@bootlin.com>
Subject: Re: [PATCH RFT 0/2/2] mtd: hyperbus: add Renesas RPC-IF driver
Date: Thu, 20 Feb 2020 08:46:23 +0100	[thread overview]
Message-ID: <20200220084623.3d5145fd@collabora.com> (raw)
In-Reply-To: <d09bb1b9-fef8-5a96-df4e-eccc228f2777@cogentembedded.com>

On Wed, 19 Feb 2020 23:13:36 +0300
Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> wrote:

> > One way would be to extend spi_mem_op to support above template along
> > with a new field to distinguish SPI NOR vs HyperFlash protocol. HyperBus
> > core can then register a spi_device and use spi-mem ops to talk to
> > controller driver.  
> 
>    We have discussed this idea with Mark Brown, the SPI maintainer, and
> he wasn't terribly impressed (I've invited him to #mtd -- his nick is
> broonie and mine is headless, I'm also adding him to CC:).
> 
> > So, I suggest making Renesas RPC-IF backend a full fledged spi-mem
> > driver (instead of driver/memory) and use extended spi_mem_op to support
> > HyperFlash.  
> 
>    I don't think cramming support for the different flash busses into
> the SPI drivers is a good idea...

That's what I thought at first (SPI and Hyperflash seemed different
enough to not merge them), then I had a look at Vignesh's HyperFlash
presentation [1], and there's one aspect that made me reconsider this
PoV. Slide 25 (xSPI compliant HyperFlash): having devices bouncing from
one driver to another depending on the mode they operate in is likely to
be painful to handle. Not to mention that Octo+DTR is similar to
HyperBus from an HW PoV (at the PHY level, they both have CS, CLK,
DQS/RWDS, DQ/IO[0:7] signals, only the protocol differs).

[1]https://elinux.org/images/3/38/HBMC-v1.pdf

______________________________________________________
Linux MTD discussion mailing list
http://lists.infradead.org/mailman/listinfo/linux-mtd/

  parent reply	other threads:[~2020-02-20  7:46 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-29 20:32 [PATCH RFT 0/2] Add RPC-IF HyperFlash driver Sergei Shtylyov
2020-01-29 20:37 ` [PATCH RFT 1/2] mtd: hyperbus: move direct mapping setup to AM654 HBMC driver Sergei Shtylyov
2020-03-13  5:21   ` Vignesh Raghavendra
2020-01-29 20:39 ` [PATCH RFT 0/2/2] mtd: hyperbus: add Renesas RPC-IF driver Sergei Shtylyov
2020-02-03  4:59   ` Vignesh Raghavendra
2020-02-03 11:46     ` Sergei Shtylyov
2020-02-07 12:59   ` Behme Dirk (CM/ESO2)
2020-02-07 19:09     ` Sergei Shtylyov
2020-02-07 19:31       ` Dirk Behme
2020-02-07 20:17         ` Sergei Shtylyov
2020-02-10  9:18           ` Behme Dirk (CM/ESO2)
2020-02-18  4:00   ` Vignesh Raghavendra
2020-02-18  7:12     ` Behme Dirk (CM/ESO2)
2020-02-18 11:11       ` Vignesh Raghavendra
2020-02-20 18:30         ` Sergei Shtylyov
2020-02-24  5:27           ` Vignesh Raghavendra
2020-02-19 20:13     ` Sergei Shtylyov
2020-02-20  6:05       ` Vignesh Raghavendra
2020-02-20  7:46       ` Boris Brezillon [this message]
2020-02-20  7:49         ` Boris Brezillon

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=20200220084623.3d5145fd@collabora.com \
    --to=boris.brezillon@collabora.com \
    --cc=broonie@kernel.org \
    --cc=dirk.behme@de.bosch.com \
    --cc=linux-mtd@lists.infradead.org \
    --cc=miquel.raynal@bootlin.com \
    --cc=richard@nod.at \
    --cc=sergei.shtylyov@cogentembedded.com \
    --cc=vigneshr@ti.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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.