aic94xx: Supermicro motherboards support

Hello,

The aic94xx driver in current mainline kernel don't work with controllers integrated in some of Supermicro motherboards (i have tested only on X6DHR-3G2) due to two reasons:
- driver do not contain corresponding PCI id (9005:041F)
- driver can not find flash on controller.

Patches which i send now ordered to resolve this problems.

First one is a simple and just add pci id, but second one is a bit controversial.

The following code from function asd_flash_getid (aic94xx_sds.c)

	reg = asd_read_reg_dword(asd_ha, EXSICNFGR);

        if (!(reg & FLASHEX)) {
                ASD_DPRINTK("flash doesn't exist\n");
                return -ENOENT;
        }

failed with error on controllers in supermicro motherboards. Looks like flag FLASHEX did not set on such devices, however flash chip present and without above if statement in code drivers works normally on supermicro controllers.

As i found this code was commented out in original driver by Luben Tuikov with following comment:

/* Early (current?) SuperMicro mainboards, X6DHR-3G2 and X6DH3-G2
have a bug whereby RS104 is missing (not installed) and RS103 is installed, causing FLASHEX to be 0. */
/* if (!(reg & FLASHEX)) { */
/* ASD_DPRINTK("flash doesn't exist\n"); */
/* return -ENOENT; */
/* } */

May be it is possible to write separate code for checking availability of flash chip especially for supermicro motherboards, but i don't know hot it possible and don't know what is RS104, RS103 and difference between it.

But more likely that check of FLASHEX can be removed safely from code

because below there is another more generic check for flash chip via pci config probe.

This solution works perfect in my case, also it was in original code, however i think this second patch would be tested on some other varieties of aic94xx hardware.

--
Sergey Kononenko
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Quoted 11 lines

As i found this code was commented out in original driver by Luben Tuikov with following comment:

/* Early (current?) SuperMicro mainboards, X6DHR-3G2 and X6DH3-G2
have a bug whereby RS104 is missing (not installed) and RS103 is installed, causing FLASHEX to be 0. */
/* if (!(reg & FLASHEX)) { */
/* ASD_DPRINTK("flash doesn't exist\n"); */
/* return -ENOENT; */
/* } */

Quoted 4 lines

May be it is possible to write separate code for checking availability of flash chip especially for supermicro motherboards, but i don't know hot it possible and don't know what is RS104, RS103 and difference between it.

RSxyz stands for "resistor xyz" in the schematic diagrams. This is a hardware bug in the (early?) SuperMicro mainboards. It dates from last year, 20 October 2005.

Quoted 11 lines · Luben Tuikov

Quoted 11 lines

As i found this code was commented out in original driver by Luben Tuikov with following comment:

/* Early (current?) SuperMicro mainboards, X6DHR-3G2 and X6DH3-G2
have a bug whereby RS104 is missing (not installed) and RS103 is installed, causing FLASHEX to be 0. */
/* if (!(reg & FLASHEX)) { */
/* ASD_DPRINTK("flash doesn't exist\n"); */
/* return -ENOENT; */
/* } */

Quoted 8 lines

Quoted 4 lines

May be it is possible to write separate code for checking availability of flash chip especially for supermicro motherboards, but i don't know hot it possible and don't know what is RS104, RS103 and difference between it.

RSxyz stands for "resistor xyz" in the schematic diagrams. This is a hardware bug in the (early?) SuperMicro mainboards. It dates from last year, 20 October 2005.

This wouldn't be the first (or last I'm sure) time a hardware manufacturer didn't properly set up the external resistors that signal to the chip whether or not certain options are installed. In the past I've done searches of the PCI device space looking for specific northbridge/southbridge pairs so I would know when to ignore certain hardware indicators based upon buggy motherboard setups.