On Tuesday 03 October 2006 9:08 am, Andrea Paterniani wrote:
> Here some questions and answers to your comments, (please consider I'm nearly new to kernel programming).
>
>
>
> > ...
> > ug. Why not simply open-code
> >
> > readl(addr + DATA);
>
> I found usefull to define macros to use inside code something like
> rd_CONTROL(regs)
> instead of
> readl(regs + 0x08)
> since to me the macro sounds more friendly.
> Should I have to adhere to some standard ?
The standards are more or less to avoid creating namespace clutter,
and to make explicit where register access happens. Defining new
macros violates the former; not being able to tell where the chip
registers are accessed (because they're wrapped in macros) violates
the latter.
> > The use of loops_per_jiffy seems inappropriate. That's an IO-space read in
> > there, which is slow. This timeout will be very long indeed.
>
> Please suggest me what it's more appropriate.
Pick a constant, use it.
> > I see tasklets being scheduled, but no tasklet_disable() or tasklet_kill(),
> > etc. Is this driver racy against shutdown or rmmod?
>
> Do you mean I should use tasklet_kill() inside spi_imx_remove ?
That's how I read it. :)
> > > + drv_data->rd_data_phys = (dma_addr_t)res->start;
> >
> > I don't think it's correct to cast a kernel virtual address straight to a
> > dma_addr_t.
>
> File include/asm-arm/types.h defines
> typedef u32 dma_addr_t;
> Also I think that for ARM architecture resource_size_t in practice
> is u32 since CONFIG_RESOURCES_64BIT isn't defined.
> Is this construction correct ? If not what should I do ?
I think it's correct; it's certainly standard for converting physical
addresses to DMA addresses. (Andrew got that one wrong; resource
addresses are physical, not virtual.)
- Dave
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