Re: [PATCH] Linux Secondary Slave IDE timings

[Andre Hedrick]

It is a valid and correct fix.
There must have been a bug or something in an odd compiler, but the reason
for the <> | order problem escapes me now.
The verification came from a commumication I had with the author of the
Intel programmer docs.

I hope my comments do not kill the patch.

Regards,

Andre Hedrick
Linux Disk Certification Project                Linux ATA Development

On Tue, 26 Feb 2002, Daniel Quinlan wrote:

> This fix is from Dave Bogdanoff <[e-mail]>.
> 
> Linux incorrectly sets up IDE timings for secondary slave drives on PC
> systems that use Intel PIIX Southbridges.
> 
> This will correctly shift IDE slave PCI timings for register 44h so
> that:
> 
>  - secondary slave (drive1) uses bits 4-7
>  - primary slave   (drive1) uses bits 0-3
> 
> (The addition of the parentheses is needed so the shift will take
> place after the bitwise-or.  Without the parentheses, the shift will
> incorrectly always take place before the bitwise-or.)
> 
> --- linux/drivers/ide/piix.c.orig	Tue Jan 29 23:26:55 2002
> +++ linux/drivers/ide/piix.c	Tue Jan 29 23:27:33 2002
> @@ -258,8 +258,8 @@
>  			master_data = master_data | 0x0070;
>  		pci_read_config_byte(HWIF(drive)->pci_dev, slave_port, &slave_data);
>  		slave_data = slave_data & (HWIF(drive)->index ? 0x0f : 0xf0);
> -		slave_data = slave_data | ((timings[pio][0] << 2) | (timings[pio][1]
> -					   << (HWIF(drive)->index ? 4 : 0)));
> +		slave_data = slave_data | (((timings[pio][0] << 2) | timings[pio][1])
> +					   << (HWIF(drive)->index ? 4 : 0));
>  	} else {
>  		master_data = master_data & 0xccf8;
>  		if (pio > 1)
> -
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