Alan wrote:
> O> Wouldn't it be better to have ->determine_xfer_mask() and
>> ->set_specific_mode() than having two somewhat overlapping callbacks?
>> Or is there some problem that can't be handled that way?
>
> I'm not sure I follow what you are suggesting - can you explain further.
>
> Right now ->set_mode does all the policy management with regards to
> picking the right modes which is sometimes done by the usual ATA rules
> and sometimes by card specific code.
>
> ->set_specific_mode does no policy work but merely sets up a mode.
>
> The default behaviour of ->set_mode() is the ATA mode selection by best
> mode available, and this function is normally not provided by a driver.
>
> The default behaviour of ->set_specific_mode() is to verify the mode is
> valid then issue ->set_pio|dma_mode() (for both devices in case a timing
> change on both is triggered). This function is overridable because of
> things like IT821x where the IDE mode is imaginary.
What I was thinking about was something like the following.
* ops
unsigned int (*determine_xfer_mask)(struct ata_device *dev);
int (*set_specific_mode)(struct ata_device *dev,
unsigned int xfer_mode);
* during init and EH
if (init) {
ap->xfer_mask &= ops->determine_xfer_mask(dev);
DETERMINE best_mode;
}
if (ap->ehi.target_mode && valid)
mode = ap->ehi.target_mode;
else
mode = best_mode;
rc = ops->set_specific_mode(dev, mode);
* when the user issues SET_XFERMODE, in the issue path
if (command is SET_XFERMODE) {
if (mode is invalid)
fail;
ap->ehi.target_mode = user_specified_mode;
ata_port_schedule_eh(ap);
done;
}
To sum up,
1. separate supported mode detection and mode programming such that we
can use the same programming path for both init and handling user-issued
SET_XFERMODE.
2. group all mode programming callbacks (->set_piomode, ->set_dmamode
and ->post_set_mode into ->set_specific_mode) into ->set_specific_mode
to allow more flexibility and replace ->set_mode.
3. make sure all xfer mode programming is done in EH. this will ease
support for weird controllers (e.g. cross-port synchronization).
Thanks.
--
tejun
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