Re: [PATCH 1/1] hw/ide: share bmdma read and write functions between piix.c and via.c

[Liav Albani]

On 2/19/22 17:57, BALATON Zoltan wrote:
> On Sat, 19 Feb 2022, BALATON Zoltan wrote:
> > Maybe even the first if that's already contained in the default 
> > function could be avoided with some reorganisation like
> >
> > if (size == 1) {
> >    remaining switch cases to set val
> > } else {
> >    val = bmdma_default_read();
> > }
>
> On second thought this misses the cases where size == 1 and addr is 
> those handeled in bmdma_default_read so one would still need the 
> default case in the if part and then it's not much better than 
> duplicating the if. Maybe calling the default first, then handling the 
> remaining cases, like
>
> val = bmdma_default_read();
> if (size == 1) {
>     remaining switch cases to set val
> }
> return val;
>
> is the simplest and avoids the duplicated if. (Now we only have two 
> trace messages instead of one but that's probably not a problem as 
> it's only a debugging aid.
Hmm, is it OK though to have two trace messages? I'm not against it, but 
if someone tries to use the debug messages to see what's going on, it's 
better to not have two of the same message as it will confuse people. We 
definitely don't want that to happen.

So, let's keep it simple (and remove code duplications) but also let's 
do that correctly, to ensure that in the view of the developer that uses 
the debug messages, it all seem clear and neat :)

> > but I wasn't sure that won't change anything so may need a bit more 
> > thought.
> >
> > > > > Signed-off-by: Liav Albani <liavalb@gmail.com>
> > > > > ---
> > > > > hw/ide/pci.c         | 47 ++++++++++++++++++++++++++++++++++++++++
> > > > > hw/ide/piix.c        | 50 ++-----------------------------------------
> > > > > hw/ide/via.c         | 51 
> > > > > ++------------------------------------------
> > > > > include/hw/ide/pci.h |  4 ++++
> > > > > 4 files changed, 55 insertions(+), 97 deletions(-)
> > > > >
> > > > > diff --git a/hw/ide/pci.c b/hw/ide/pci.c
> > > > > index 84ba733548..c8b867659a 100644
> > > > > --- a/hw/ide/pci.c
> > > > > +++ b/hw/ide/pci.c
> > > > > @@ -502,6 +502,53 @@ static const struct IDEDMAOps bmdma_ops = {
> > > > >     .reset = bmdma_reset,
> > > > > };
> > > > >
> > > > > +uint64_t bmdma_default_read(void *opaque, hwaddr addr,
> > > > > +                           unsigned size)
> > > >
> > > > Indentation off? Also everywhere else, usually we indent not with 
> > > > the parenthesis but with the list within. (Auto indent in most 
> > > > editors does that probably.)
> > > I guess you mean that it should be:
> > >
> > > +uint64_t bmdma_default_read(void *opaque, hwaddr addr,
> > > +                                                unsigned size)
> > >
> > > Like this?
> >
> > No, like the code you've moved had it. The split line should start 
> > after the ( not on the same column. So:
> >
> > uint64_t bmdma_default_read(void *opaque, hwaddr addr,
> >                             unsigned size)
> >
> > but this line does not need to be split at all as it fits within 80 
> > chars so better to keep it one line and only split where needed.
> >
> > > I'm using Visual Studio Code, so I might not have the correct 
> > > settings for this editor with QEMU.
> > > The checkpatch script doesn't complain on style issues, so what can 
> > > I do to make this correct?
> >
> > If checkpatch is happy then probably not a problem but just look at 
> > how code is indented on other places and follow the same. The coding 
> > style doc may have some words on it too. I don't know what setting 
> > Visual Studio might need.

OK. I'll align it to the character after the start of the parenthesis. 
I'll take a look into other code snippets in QEMU, but at least in the 
IDE code, there are lots of code style issues (the checkpatch script 
says so) so I'll probably look into other parts of QEMU to see how it goes.

I'll take this a bit slow, as I wanted to send v2 today. This is 
probably not a good idea as we should let people to see this and maybe 
to let the maintainer (John) to look into this and put his comments on 
this too. I'll give this a couple of days - no rush here, although I'd 
be very happy to see things going forward as soon as possible, so we 
merge this patch and then going back to the ich6-ide patch, and then 
hopefully more patches to the IDE code to add more features and fixes in 
this part of QEMU codebase.

Thanks again for the suggestions, these are awesome and I really 
appreciate the effort you put into these!

Best regards,
Liav