From: David Brownell <david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
To: Daniel Ribeiro <drwyrm-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Cc: Stefan Schmidt <stefan-4Bgg8jF3iZdg9hUCZPvPmw@public.gmane.org>,
eric.y.miao-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org,
linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org,
sameo-RWuK6r/cQWRpLGFMi4vTTA@public.gmane.org,
linux-arm-kernel-xIg/pKzrS19vn6HldHNs0ANdhmdF6hFW@public.gmane.org,
Stefan Schmidt
<stefan-OrPQZGeq07wqhVmZOOOmNx2eb7JE58TQ@public.gmane.org>
Subject: Re: [patch 05/14] mfd: PCAP2 driver
Date: Sat, 22 Nov 2008 20:59:59 -0800 [thread overview]
Message-ID: <200811222059.59806.david-b@pacbell.net> (raw)
In-Reply-To: <1227411537.3148.22.camel@brutus>
On Saturday 22 November 2008, Daniel Ribeiro wrote:
> > - You should make ezx_pcap_write() and ezx_pcap_read() switch
> > over to spi_write_then_read(), to ensure it's never doing
> > DMA to/from the stack. I see a byte-order dependency too...
>
> I tried spi_write_then_read before, but it didn't work. I supposed it
> was because it was doing 2 transfers as the second transfer rx_buf
> always came zeroed.
You may have been using it wrong. Also, verify against
current kernels ... there have been bugfixes to pxa2xx_spi.
> I see that commit
> f9b90e39cbc5c4d6ef60022fd1f25d541df0aad1 changed it to do a single
> transfer, so i will try it again.
Unless it needs the full duplex capability of SPI, then
you should be able to make write_then_read work ... on
the other hand, if you do need full duplex, then you
should address the DMA. (And byteswapping, either way.)
> > - If you're going to mark the probe() as __devinit, then mark
> > the remove() as __devexit and use __devexit_p() in the driver
> > struct.
>
> Ok. Shouldn't i use __init instead?
I wouldn't. There are ways that the probe() could be called
more than once -- e.g. after rebinding either of the relevant
SPI drivers through sysfs, or after rmmod/modprobe of the SPI
master controller driver -- and using an __init annotation
would make that point to memory that's unlikely to still hold
that code.
- Dave
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next prev parent reply other threads:[~2008-11-23 4:59 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20081121160403.073751031@dodger.lab.datenfreihafen.org>
2008-11-21 16:04 ` [patch 05/14] mfd: PCAP2 driver stefan-OrPQZGeq07wqhVmZOOOmNx2eb7JE58TQ
[not found] ` <20081121160521.016544616-cQQG9CVUopzFITZdfPi31ZcF1vblOVnWhIvA6WVW+J8@public.gmane.org>
2008-11-22 5:25 ` David Brownell
2008-11-22 14:01 ` [spi-devel-general] " Eric Miao
[not found] ` <f17812d70811220601p1d7af668mf3265224179753ab-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2008-11-22 15:54 ` Daniel Ribeiro
2008-11-22 19:08 ` David Brownell
[not found] ` <200811221108.54331.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-11-22 23:29 ` Stefan Schmidt
[not found] ` <200811212125.49068.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-11-22 17:12 ` Daniel Ribeiro
2008-11-22 19:19 ` David Brownell
[not found] ` <200811221119.27981.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-11-22 23:33 ` Stefan Schmidt
[not found] ` <20081122233356.GC24437-OrPQZGeq07wqhVmZOOOmNx2eb7JE58TQ@public.gmane.org>
2008-11-22 23:58 ` David Brownell
[not found] ` <200811221558.03915.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-11-23 0:33 ` Stefan Schmidt
[not found] ` <20081123003306.GE24437-OrPQZGeq07wqhVmZOOOmNx2eb7JE58TQ@public.gmane.org>
2008-11-23 2:19 ` David Brownell
[not found] ` <200811221819.53186.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-11-23 3:38 ` Daniel Ribeiro
2008-11-23 4:59 ` David Brownell [this message]
[not found] ` <200811222059.59806.david-b-yBeKhBN/0LDR7s880joybQ@public.gmane.org>
2008-11-23 7:06 ` Daniel Ribeiro
2008-11-23 8:26 ` David Brownell
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