Hi,
sorry not to have answered sooner.
On Tuesday 09 June 2009 00:05:10 Karicheri, Muralidharan wrote:
> > > +
> > > +/* register access routines */
> > > +static inline u32 regr(u32 offset)
> > > +{
> > > + if (offset <= ccdc_addr_size)
> >
> > This should be <.
> >
> > > + return __raw_readl(ccdc_base_addr + offset);
> > > + else {
> > > + dev_err(dev, "offset exceeds ccdc register address space\n");
> > > + return -1;
> > > + }
> > > +}
> > > +
> > > +static inline u32 regw(u32 val, u32 offset)
> > > +{
> > > + if (offset <= ccdc_addr_size) {
> >
> > This should be <.
>
> [MK] I removed above two checks since we are getting the required IO block
> mapped and this check is not needed. if some reason there is an offset
> outside the valid range, it is a bug and will be caught through oops,
> right?.
Not necessarily. I'm not sure how ioremap works exactly, but accessing data
outside the remapped region might end up being a valid access. Anyway this
shouldn't happen unless a bug creeps in the driver. If you want to validate
the size it should be done in ccdc_set_ccdc_base instead, but that's not
really required.
> > > + __raw_writel(val, ccdc_base_addr + offset);
> > > + return val;
> > > + } else {
> > > + dev_err(dev, "offset exceeds ccdc register address space\n");
> > > + return -1;
> > > + }
> > > +}
> >
> > Can't you check that ccdc_addr_size is big enough in ccdc_set_ccdc_base ?
> > The read/write access functions could then be made much simpler.
>
> [MK] See above comment
>
> > > + }
> > > +
> > > + switch (ctrl->id) {
> > > + case CCDC_CID_R_GAIN:
> > > + gain->r_ye = ctrl->value & CCDC_GAIN_MASK;
> > > + break;
> > > + case CCDC_CID_GR_GAIN:
> > > + gain->gr_cy = ctrl->value & CCDC_GAIN_MASK;
> > > + break;
> > > + case CCDC_CID_GB_GAIN:
> > > + gain->gb_g = ctrl->value & CCDC_GAIN_MASK;
> > > + break;
> > > +
> > > + case CCDC_CID_B_GAIN:
> > > + gain->b_mg = ctrl->value & CCDC_GAIN_MASK;
> > > + break;
> >
> > case CCDC_CID_OFFSET: ?
> >
> > > + default:
> > > + ccdc_hw_params_raw.ccdc_offset = ctrl->value &
> > > CCDC_OFFSET_MASK;
>
> [MK] default is for offset. We are validating the ids above for any of the
> checked values in the switch statement
If you're sure that the control ID is one of the above cases, use
CCDC_CID_OFFSET instead of default, the code will be easier to read.
> > > +
> > > +static void ccdc_reset(void)
> > > +{
> > > + int i;
> > > + /* disable CCDC */
> > > + dev_dbg(dev, "\nstarting ccdc_reset...");
> > > + ccdc_enable(0);
> > > + /* set all registers to default value */
> > > + for (i = 0; i <= 0x15c; i += 4)
> > > + regw(0, i);
> >
> > Ouch ! Not all registers have a 0 default value. Beside, blindly resetting
> > all registers sounds hackish. According to the documentation, the proper
> > way to reset the VPFE/VPSS is through the power & sleep controller.
>
> [MK] This function actually write default values in the registers since the
> implementation assume this. So I have renamed it as ccdc_restore_defaults().
> We don't want to reset the ccdc here, only want to write default values.
Some registers have a non-0 default value according to the datasheet.
> > > +/*
> > > + * ======== ccdc_setwin ========
> > > + *
> > > + * This function will configure the window size to
> > > + * be capture in CCDC reg
> > > + */
> > > +static void ccdc_setwin(struct ccdc_imgwin *image_win,
> > > + enum ccdc_frmfmt frm_fmt, int ppc)
> >
> > What's does ppc stand for ?
>
> [MK] per pixel count. I documented this.
>
> > > +{
> > > + int horz_start, horz_nr_pixels;
> >
> > Does horz_nr_pixels really store the number of pixels ? It seems to me it
> > counts the number of bytes. hstart and hsize would then be more
> > appropriate names.
>
> [MK]. It is storing number of pixels and the documentation say so. So names
> used are fine as per hw spec.
Then I'm puzzled by
horz_start = image_win->left << (ppc - 1);
image_win->left is a number of pixels. Shifting it left by 1 in the YUV case
will give a number of bytes.
> > > + int vert_start, vert_nr_lines;
> >
> > If the above comment is correct, this could become vstart and vsize to be
> > consistent.
>
> [MK] No change. See above
>
> > > + return 0;
> > > +}
> > > +static enum ccdc_buftype ccdc_get_buftype(void)
> > > +{
> > > + if (ccdc_if_type == VPFE_RAW_BAYER)
> > > + return ccdc_hw_params_raw.buf_type;
> > > + return ccdc_hw_params_ycbcr.buf_type;
> > > +}
> > > +
> > > +static int ccdc_enum_pix(enum vpfe_hw_pix_format *hw_pix, int i)
> > > +{
> > > + int ret = -EINVAL;
> > > + if (ccdc_if_type == VPFE_RAW_BAYER) {
> > > + if (i < CCDC_MAX_RAW_BAYER_FORMATS) {
> > > + *hw_pix = ccdc_raw_bayer_hw_formats[i];
> >
> > How does this compare to memcpy in term of code size and run time ?
>
> [MK] not sure what you are asking here.
I was wondering which of
*hw_pix = ccdc_raw_bayer_hw_formats[i];
and
memcpy(hw_pix, &ccdc_raw_bayer_hw_formats[i], sizeof(*hw_pix));
lead to a smaller code size and run time. It's a minor issue, it can always be
changed later if memcpy is found to be smaller and faster.
> > > + return 0;
> > > +}
> > >
> > > +#define CCDC_WIN_PAL {0, 0, 720, 576}
> > > +#define CCDC_WIN_VGA {0, 0, 640, 480}
> > > +
> >
> > Most enumerations have too generic names, especially for a header exported
> > to userspace. Beside, you shouldn't use enumerations in userspace <->
> > kernelspace APIs, especially on ARMs. Use #define instead, or, even
> > better, integers where possible (for the sample length for instance).
>
> [MK], renamed all types with ccdc_ prefix. There are numerous parameter
> types here and replacing them with integer will add a lot of code to check
> for their valid values. For example sample length can be 1 or 2 or 4 or 8
> or 16 pixels. If I use integer, I need to make sure user doesn't set it
> other than the values listed above. I don't see a point here. Anyways, I
> have added a TODO, if something come out of this discussion and we decide
> to change it. At this time, I don't see why we should do it.
Ok.
We're at last converging :-) The only issue I'd like to see addressed before
the code gets committed in the Davinci git tree is the pixels vs. bytes
comment in ccdc_setwin. I might be wrong in my understanding, in which case
there's no problem, but I'd like to understand it.
Best regards,
Laurent Pinchart
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