On Tue, 2005-11-22 at 22:43 +0100, Kars de Jong wrote: > I don't really understand the current mechanism. It seems to result in > different behaviour for BE systems depending on the definition of > CONFIG_53C700_LE_ON_BE. > > I would have expected the behaviour on BE systems without defining > CONFIG_53C700_LE_ON_BE to be the same as on BE systems with > CONFIG_53C700_LE_ON_BE defined but with hostdata->force_le_on_be set to > 0. > > Was this driver ever used on BE systems without CONFIG_53C700_LE_ON_BE > being defined? > > For reference: > > BE with CONFIG_53C700_LE_ON_BE defined but hostdata->force_le_on_be set > to 0: > > /* This is terrible, but there's no raw version of ioread32. That means > * that on a be board we swap twice (once in ioread32 and once again to > * get the value correct) */ > #define bS_to_io(x) ((hostdata->force_le_on_be) ? (x) : cpu_to_le32(x)) > > evaluates to > 0 ----------> cpu_to_le32(x) > > And without CONFIG_53C700_LE_ON_BE defined: > > #define bS_to_io(x) (x) > > I think this last define should be cpu_to_le32() as well, then the > driver would work on m68k out-of-the-box. > > James, can you comment on this? OK, let me try to explain. ioread/write32 came with a slight design flaw in that it *always* converts to LE. By and large, no-one notices this because almost every platform has the PCI bus, which is LE. However, PA also has the GSC bus, which is BE. We already introduced the ioread/write<n>be macros which work for a BE bus. You're right, the only current BE consumer of the driver is PA-RISC, which has a cockup on one of the 53c700 chips which is wired in LE mode on the BE GSC bus, so we need that flag. I assume your problems is also that the 53c7x0 chip on the MAC is also on a BE bus, so I think what you want is another flag: 53c700_BE_BUS which causes all the io macros to be ioread/write<n>be. Which will avoid the nasty double swap we do on PA. James - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
