linux-kernel - Re: [05/27] ALSA: lx6464es - fix device communication via command bus

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Message-ID: <1561513.9b6lVaYVip@moka>
Date:	Wed, 07 Dec 2011 18:13:08 +0100
From:	Tim Blechmann <tim@...ngt.org>
To:	Greg KH <gregkh@...e.de>
Cc:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Takashi Iwai <tiwai@...e.de>
Subject: Re: [05/27] ALSA: lx6464es - fix device communication via command bus

it is not really necessary to apply this patch to 2.6.32, as the problem was 
introduced by a change to the memcpy_*_io functions that was introduced in 
2.6.34.

otoh, it doesn't harm, either.

On Wednesday 07 December 2011 08:54:38 Greg KH wrote:
> 2.6.32-longterm review patch.  If anyone has any objections, please let me
> know.
> 
> ------------------
> 
> From: Tim Blechmann <tim@...ngt.org>
> 
> commit a29878553a9a7b4c06f93c7e383527cf014d4ceb upstream.
> 
> commit 6175ddf06b6172046a329e3abfd9c901a43efd2e optimized the mem*io
> functions that have been used to send commands to the device. these
> optimizations somehow corrupted the communication with the lx6464es,
> that resulted the device to be unusable with kernels after 2.6.33.
> 
> this patch emulates the memcpy_*_io functions via a loop to avoid these
> problems.
> 
> Signed-off-by: Tim Blechmann <tim@...ngt.org>
> LKML-Reference: <4ECB5257.4040600@...isch.de>
> Signed-off-by: Takashi Iwai <tiwai@...e.de>
> Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
> 
> ---
>  sound/pci/lx6464es/lx_core.c |   16 ++++++++++++----
>  1 file changed, 12 insertions(+), 4 deletions(-)
> 
> --- a/sound/pci/lx6464es/lx_core.c
> +++ b/sound/pci/lx6464es/lx_core.c
> @@ -80,8 +80,12 @@ unsigned long lx_dsp_reg_read(struct lx6
> 
>  void lx_dsp_reg_readbuf(struct lx6464es *chip, int port, u32 *data, u32
> len) {
> -	void __iomem *address = lx_dsp_register(chip, port);
> -	memcpy_fromio(data, address, len*sizeof(u32));
> +	u32 __iomem *address = lx_dsp_register(chip, port);
> +	int i;
> +
> +	/* we cannot use memcpy_fromio */
> +	for (i = 0; i != len; ++i)
> +		data[i] = ioread32(address + i);
>  }
> 
> 
> @@ -94,8 +98,12 @@ void lx_dsp_reg_write(struct lx6464es *c
>  void lx_dsp_reg_writebuf(struct lx6464es *chip, int port, const u32 *data,
>  			 u32 len)
>  {
> -	void __iomem *address = lx_dsp_register(chip, port);
> -	memcpy_toio(address, data, len*sizeof(u32));
> +	u32 __iomem *address = lx_dsp_register(chip, port);
> +	int i;
> +
> +	/* we cannot use memcpy_to */
> +	for (i = 0; i != len; ++i)
> +		iowrite32(data[i], address + i);
>  }
--
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