linux-kernel - Re: [PATCHv2] sound: fix emu8000 DRAM sized 512 KiB too small

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Date:	Tue, 28 Aug 2012 20:01:22 +0200
From:	Takashi Iwai <tiwai@...e.de>
To:	David Flater <vger@...terco.com>
Cc:	Alsa Devel <alsa-devel@...r.kernel.org>,
	Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCHv2] sound: fix emu8000 DRAM sized 512 KiB too small

At Mon, 27 Aug 2012 22:25:21 -0400,
David Flater wrote:
> 
> v2:  Fixed result still wrong in the case of 512 KiB DRAM.  Oops.
> 
> Applicable to 3.5.3 mainline.
> 
> In emu8000.c, size_dram determines the amount of memory on the sound card by
> doing write/readback tests starting at 512 KiB and incrementing by 512 KiB.
> On success, detected_size is updated to the successful address and testing
> continues.  On failure, the loop is immediately exited.  The resulting
> detected_size is 512 KiB too small except in two special cases:
> 
> 1. If there is no memory, the initial 0 value of detected_size is used, which
>    is correct.
> 2. If the address space wraps around, detected_size is updated before the
>    bailout, so the result is correct.
> 
> The patch corrects all cases and was tested with an AWE64 Gold.  Before:
>   EMU8000 [0x620]: 3584 Kb on-board memory detected
>   asfxload 4GMGSMT.SF2 (4174814 B) fails.
> After:
>   EMU8000 [0x620]: 4096 Kb on-board memory detected
>   asfxload 4GMGSMT.SF2 succeeds.
> 
> I do not have a card with 512 KiB to test with, but by forcibly enabling the
> added conditional I verified on the AWE64 Gold that it detects 512 KiB
> (successfully reading from the first memory location) and does not hang the
> card.
> 
> C.f. Bug 46451 https://bugzilla.kernel.org/show_bug.cgi?id=46451
> 
> Signed-off-by: David Flater <dave@...terco.com>

Thanks, applied.


Takashi


> ---
> 
> --- linux-3.5.3-nameless/sound/isa/sb/emu8000.c.orig	2012-08-25 22:32:13.000000000 -0400
> +++ linux-3.5.3-nameless/sound/isa/sb/emu8000.c	2012-08-27 22:06:15.729510037 -0400
> @@ -417,9 +417,6 @@ size_dram(struct snd_emu8000 *emu)
>  		EMU8000_SMLD_READ(emu); /* discard stale data  */
>  		if (EMU8000_SMLD_READ(emu) != UNIQUE_ID2)
>  			break; /* no memory at this address */
> -
> -		detected_size = size;
> -
>  		snd_emu8000_read_wait(emu);
>  
>  		/*
> @@ -432,6 +429,18 @@ size_dram(struct snd_emu8000 *emu)
>  		if (EMU8000_SMLD_READ(emu) != UNIQUE_ID1)
>  			break; /* we must have wrapped around */
>  		snd_emu8000_read_wait(emu);
> +
> +		/* Otherwise, it's valid memory. */
> +		detected_size = size + 512 * 1024;
> +	}
> +
> +	/* Distinguish 512 KiB from 0. */
> +	if (detected_size == 0) {
> +		snd_emu8000_read_wait(emu);
> +		EMU8000_SMALR_WRITE(emu, EMU8000_DRAM_OFFSET);
> +		EMU8000_SMLD_READ(emu); /* discard stale data  */
> +		if (EMU8000_SMLD_READ(emu) == UNIQUE_ID1)
> +			detected_size = 512 * 1024;
>  	}
>  
>  	/* wait until FULL bit in SMAxW register is false */
> 
> --
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