* Kevin Hilman <khilman@xxxxxxxxxxxxxxxxxxx> [100430 14:56]: > "Pandita, Vikram" <vikram.pandita@xxxxxx> writes: > > [...] > > >>>> > --- a/arch/arm/kernel/head.S > >>>> > +++ b/arch/arm/kernel/head.S > >>>> > @@ -328,6 +328,16 @@ __create_page_tables: > >>>> > add r0, r4, #0xd8000000 >> 18 > >>>> > str r3, [r0] > >>>> > #endif > >>>> > +#if defined(CONFIG_MACH_OMAP_ZOOM2) || > >>defined(CONFIG_MACH_OMAP_ZOOM3) > >>>> > + /* > >>>> > + * Zoom2 and Zoom3 have UARTs only on the debug board. > >>>> > + * The debug board is connected to the GPMC. > >>>> > + */ > >>>> > + add r0, r4, #0xfa000000 >> 18 > >>>> > + orr r0, r0, #0x00400000 >> 18 @ ZOOM_UART_VIRT > >>>> > + orr r3, r7, #0x10000000 @ ZOOM_UART_BASE > >>>> > + str r3, [r0] > >>>> > +#endif > >>>> > >>>> I don't see why this part is needed. The same mapping is done using > >>>> the .io_pg_offset in the machine description which is done just before > >>>> this in head.S > >>> > >>> That mapping does not cover the GPMC area where this UART is. > >> > >>Hmm, then shouldn't that be fixed? I understood the .phys_io and and > >>.io_pg_offset fields of the mach_desc to be specifically for mapping > >>the early UART, and nothing else. > > > > Here is the problem - with current approach we need two mappings to > > happen and the MACHINE_START() code allows for only one via > > .io_pg_offset and .phys_io > > > > Why: > > > Tony's approach is to pass the information about the debug uart > > number from the UART1 Scratchpad register. > > > > this introduces a dependency that > > UART1 registers also be mapped (virt<->phy). > > > > So for Tony's approach to work, .phys_io/.io_pg_offset continued to > > have 0x4800000 based mapping and for external uart zoom3 port, > > create this extra mapping. > > > > So find a better way from compressed.S to pass the uart number to > > kernel, and we can solve the problem. > > Ah, yet another reason to use a memory location instead of UART1 SCR > to pass the UART info (c.f. [1]) That should work if we don't need to access any L4 registers early on before .map_io. Regards, Tony > Kevin > > [1] http://marc.info/?l=linux-omap&m=127266219130713&w=2 -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
