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From: Segher Boessenkool <segher@kernel.crashing.org>
To: David Woodhouse <dwmw2@infradead.org>
Cc: Sergei Shtylyov <sshtylyov@ru.mvista.com>,
	linuxppc-dev@ozlabs.org, linux-mtd@lists.infradead.org,
	Milton Miller <miltonm@bga.com>
Subject: Re: [PATCH] powerpc: Create "rom" (MTD) device prpmc2800
Date: Thu, 7 Jun 2007 17:55:44 +0200	[thread overview]
Message-ID: <18fbfbaf113ab76b602d279848d9b405@kernel.crashing.org> (raw)
In-Reply-To: <1181228442.2785.60.camel@pmac.infradead.org>

> Any representation of flash devices in the device-tree should ideally
> have 'bus width' and 'interleave' properties to contain this
> information.
>
> The 'bus width' cannot necessarily be inferred, especially where a 
> given
> bus can be configured to allow multiple sizes of access. It's purely a
> function of how the flash chips are wired up. That's why we actually
> call it 'bank width', not 'bus width' in the Linux code.

Ah, "bank width" as in "bus width" per chip select.  I see.

So I think the best thing to have would be

	compatible      "cfi-flash"
	bank-width      like you said
	device-width    width of a single flash device
	reg             complete address range of this thing

and then the Linux OF CFI flash code / MTD code just keeps
on probing devices from that address range until it has it
filled.

Sounds good / comments / anything I missed?


Segher

WARNING: multiple messages have this Message-ID (diff)
From: Segher Boessenkool <segher@kernel.crashing.org>
To: David Woodhouse <dwmw2@infradead.org>
Cc: linuxppc-dev@ozlabs.org, linux-mtd@lists.infradead.org,
	Milton Miller <miltonm@bga.com>
Subject: Re: [PATCH] powerpc: Create "rom" (MTD) device prpmc2800
Date: Thu, 7 Jun 2007 17:55:44 +0200	[thread overview]
Message-ID: <18fbfbaf113ab76b602d279848d9b405@kernel.crashing.org> (raw)
In-Reply-To: <1181228442.2785.60.camel@pmac.infradead.org>

> Any representation of flash devices in the device-tree should ideally
> have 'bus width' and 'interleave' properties to contain this
> information.
>
> The 'bus width' cannot necessarily be inferred, especially where a 
> given
> bus can be configured to allow multiple sizes of access. It's purely a
> function of how the flash chips are wired up. That's why we actually
> call it 'bank width', not 'bus width' in the Linux code.

Ah, "bank width" as in "bus width" per chip select.  I see.

So I think the best thing to have would be

	compatible      "cfi-flash"
	bank-width      like you said
	device-width    width of a single flash device
	reg             complete address range of this thing

and then the Linux OF CFI flash code / MTD code just keeps
on probing devices from that address range until it has it
filled.

Sounds good / comments / anything I missed?


Segher

  reply	other threads:[~2007-06-07 15:56 UTC|newest]

Thread overview: 106+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-06-02  4:30 [PATCH] powerpc: Create "rom" (MTD) device prpmc2800 Milton Miller
2007-06-02  7:39 ` Benjamin Herrenschmidt
2007-06-03 16:10   ` Sergei Shtylyov
2007-06-03 17:36     ` Segher Boessenkool
2007-06-03 18:03       ` Sergei Shtylyov
2007-06-03 18:03         ` Sergei Shtylyov
2007-06-03 18:25         ` Segher Boessenkool
2007-06-03 18:25           ` Segher Boessenkool
2007-06-03 18:36           ` Sergei Shtylyov
2007-06-03 18:36             ` Sergei Shtylyov
2007-06-03 18:46             ` Segher Boessenkool
2007-06-03 18:46               ` Segher Boessenkool
2007-06-03 19:16               ` Sergei Shtylyov
2007-06-03 19:16                 ` Sergei Shtylyov
2007-06-03 21:04         ` Benjamin Herrenschmidt
2007-06-03 21:04           ` Benjamin Herrenschmidt
2007-06-04 12:34           ` Sergei Shtylyov
2007-06-04 12:34             ` Sergei Shtylyov
2007-06-04 14:37             ` Segher Boessenkool
2007-06-04 14:37               ` Segher Boessenkool
2007-06-04 14:49               ` Sergei Shtylyov
2007-06-04 14:49                 ` Sergei Shtylyov
2007-06-07 14:53           ` David Woodhouse
2007-06-07 14:53             ` David Woodhouse
2007-06-07 15:49             ` Segher Boessenkool
2007-06-07 15:49               ` Segher Boessenkool
2007-06-07 14:47         ` David Woodhouse
2007-06-07 14:47           ` David Woodhouse
2007-06-07 15:32           ` Segher Boessenkool
2007-06-07 15:32             ` Segher Boessenkool
2007-06-02  8:53 ` Segher Boessenkool
2007-06-03 16:22   ` Sergei Shtylyov
2007-06-03 17:40     ` Segher Boessenkool
2007-06-03 18:31       ` Sergei Shtylyov
2007-06-03 18:44         ` Segher Boessenkool
2007-06-03 19:13           ` Sergei Shtylyov
2007-06-03 19:56             ` Segher Boessenkool
2007-06-03 20:26               ` Sergei Shtylyov
2007-06-04  8:07                 ` Segher Boessenkool
2007-06-04 13:34                   ` Sergei Shtylyov
2007-06-07 15:00                 ` David Woodhouse
2007-06-07 15:00                   ` David Woodhouse
2007-06-07 15:55                   ` Segher Boessenkool [this message]
2007-06-07 15:55                     ` Segher Boessenkool
2007-06-07 16:05                     ` David Woodhouse
2007-06-07 16:05                       ` David Woodhouse
2007-06-07 16:46                       ` Segher Boessenkool
2007-06-07 16:46                         ` Segher Boessenkool
2007-06-12  4:44                     ` David Gibson
2007-06-12 10:53                       ` Segher Boessenkool
2007-06-13  3:16                         ` David Gibson
2007-06-13  5:05                           ` Segher Boessenkool
2007-06-13  6:11                             ` David Gibson
2007-06-13  9:10                               ` Segher Boessenkool
2007-06-15  4:12                                 ` David Gibson
2007-06-15 11:22                                   ` Segher Boessenkool
2007-06-15  4:14                     ` David Gibson
2007-06-15  8:42                       ` Segher Boessenkool
2007-06-15  8:47                         ` David Woodhouse
2007-06-15  8:59                           ` Segher Boessenkool
2007-06-03 21:12     ` Benjamin Herrenschmidt
2007-06-03 21:12       ` Benjamin Herrenschmidt
2007-06-04  8:11       ` Segher Boessenkool
2007-06-04  8:11         ` Segher Boessenkool
2007-06-04 13:16         ` Sergei Shtylyov
2007-06-04 13:16           ` Sergei Shtylyov
2007-06-04 12:41       ` Sergei Shtylyov
2007-06-04 12:41         ` Sergei Shtylyov
2007-06-04 14:49         ` Segher Boessenkool
2007-06-04 14:49           ` Segher Boessenkool
2007-06-04 15:54           ` Sergei Shtylyov
2007-06-04 15:54             ` Sergei Shtylyov
2007-06-03 17:29 ` Sergei Shtylyov
2007-06-03 17:45   ` Segher Boessenkool
2007-06-03 18:18     ` Sergei Shtylyov
2007-06-03 18:43       ` Segher Boessenkool
2007-06-03 18:59         ` Sergei Shtylyov
2007-06-03 19:48           ` Segher Boessenkool
2007-06-03 20:10             ` Sergei Shtylyov
2007-06-04  8:02               ` Segher Boessenkool
2007-06-04 19:40 ` Mark A. Greer
  -- strict thread matches above, loose matches on Subject: below --
2007-06-01 23:20 Mark A. Greer
2007-06-02  8:46 ` Segher Boessenkool
2007-06-04 20:56 ` Mark A. Greer
2007-06-05 20:35   ` Sergei Shtylyov
2007-06-05 21:11     ` Mark A. Greer
2007-06-06 12:41       ` Sergei Shtylyov
2007-06-06 12:41         ` Sergei Shtylyov
2007-06-07 15:08         ` David Woodhouse
2007-06-07 15:08           ` David Woodhouse
2007-06-06  2:39   ` David Gibson
2007-06-07 13:30     ` Segher Boessenkool
2007-06-12  4:42       ` David Gibson
2007-06-12 10:50         ` Segher Boessenkool
2007-06-13  6:12           ` David Gibson
2007-06-13  9:13             ` Segher Boessenkool
2007-06-13  9:19               ` David Gibson
2007-06-13  9:37                 ` Segher Boessenkool
2007-06-14  4:29                   ` David Gibson
2007-06-14  8:00                     ` Segher Boessenkool
2007-06-14 12:39                     ` Sergei Shtylyov
2007-06-14 13:20                       ` Segher Boessenkool
2007-06-14 12:48           ` Sergei Shtylyov
2007-06-14 13:18             ` Segher Boessenkool
2007-06-14 12:50         ` Sergei Shtylyov
2007-06-14 13:43           ` Segher Boessenkool

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