From: Grant Likely <grant.likely@secretlab.ca>
To: John Linn <John.Linn@xilinx.com>
Cc: John Linn <linnj@xilinx.com>,
linux-serial@vger.kernel.org, jacmet@sunsite.dk,
michal.simek@petalogix.com, john.williams@petalogix.com
Subject: Re: [PATCH] [V3] uartlite: move from byte accesses to word accesses
Date: Wed, 17 Mar 2010 15:26:31 -0600 [thread overview]
Message-ID: <fa686aa41003171426p30588619h1240154ae0ba1664@mail.gmail.com> (raw)
In-Reply-To: <873097b0-5388-45b1-8483-3ef01bf8351f@SG2EHSMHS005.ehs.local>
On Wed, Mar 17, 2010 at 12:04 PM, John Linn <John.Linn@xilinx.com> wrote:
>
>
>> -----Original Message-----
>> From: John Linn
>> Sent: Wednesday, March 17, 2010 10:27 AM
>> To: 'Grant Likely'
>> Cc: linux-serial@vger.kernel.org; jacmet@sunsite.dk; michal.simek@petalogix.com;
>> john.williams@petalogix.com
>> Subject: RE: [PATCH] [V3] uartlite: move from byte accesses to word accesses
>>
>> > -----Original Message-----
>> > From: glikely@secretlab.ca [mailto:glikely@secretlab.ca] On Behalf Of Grant Likely
>> > Sent: Wednesday, March 17, 2010 10:21 AM
>> > To: John Linn
>> > Cc: linux-serial@vger.kernel.org; jacmet@sunsite.dk; michal.simek@petalogix.com;
>> > john.williams@petalogix.com
>> > Subject: Re: [PATCH] [V3] uartlite: move from byte accesses to word accesses
>> >
>> > On Wed, Mar 17, 2010 at 9:40 AM, John Linn <john.linn@xilinx.com> wrote:
>> > > Byte accesses for I/O devices in Xilinx IP is going to be less
>> > > desired in the future such that the driver is being changed to
>> > > use 32 bit accesses.
>> > >
>> > > This change facilitates using the uartlite IP over a PCIe bus
>> > > which only allows 32 bit accesses.
>> > >
>> > > Signed-off-by: John Linn <john.linn@xilinx.com>
>> > >
>> > > ---
>> > >
>> > > V2 - updated the commit message based on Peter's comments
>> > >
>> > > V3 - removed u8 casting based on Peter's comments, cleaned up and
>> > > simplified the change by using raw I/O functions rather than
>> > > using in_be32 & out_be32 functions.
>> >
>> > The __raw_{read,write}l() functions aren't the best choice here. User
>> > ioread32be(), iowrite32be() instead if you want them to work
>> > cross-architecture (see include/asm-generic/iomap.h).
>>
>> Maybe the ioread functions will work better than the in/out_be32 as they
>> were not working like I wanted.
>>
>> I'm still trying to get my head wrapped around the right I/O functions to use since there are so many
>> options.
>>
>> I'll look at your suggestions.
>
> That works ok on Powerpc, but not microblaze yet as there are still patches in the process of going into the kernel for that.
>
> Do we need to wait til those patches are in?
I'd make it broken in Kconfig on microblaze until those patches get
merged. To the best of my knowledge, the ioread/write routines are
the best functions to use for cross-architecture MMIO code.
g.
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next prev parent reply other threads:[~2010-03-17 21:26 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-17 15:40 [PATCH] [V3] uartlite: move from byte accesses to word accesses John Linn
2010-03-17 16:21 ` Grant Likely
2010-03-17 16:26 ` John Linn
2010-03-17 18:04 ` John Linn
2010-03-17 21:26 ` Grant Likely [this message]
2010-03-17 23:37 ` John Williams
[not found] ` <1d3f23371003171631x7e854ff6xd4f647b53b2dbe96@mail.gmail.com>
2010-03-18 0:01 ` Grant Likely
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