On Tue, Nov 28, 2017 at 11:33:37PM +0000, Jeremy Sowden wrote:
> On 2017-11-28, at 17:15:24 +0300, Dan Carpenter wrote:
> > On Mon, Nov 27, 2017 at 12:44:48PM +0000, Jeremy Sowden wrote:
> > > The "address" member of struct ia_css_host_data is a
> > > pointer-to-char, so define default as NULL.
> > >
> > > ---
> > > a/drivers/staging/media/atomisp/pci/atomisp2/css2400/runtime/isp_param/interface/ia_css_isp_param_types.h
> > > +++
> > > b/drivers/staging/media/atomisp/pci/atomisp2/css2400/runtime/isp_param/interface/ia_css_isp_param_types.h
> > > @@ -95,7 +95,7 @@ union ia_css_all_memory_offsets {
> > > };
> > >
> > > #define IA_CSS_DEFAULT_ISP_MEM_PARAMS \
> > > - { { { { 0, 0 } } } }
> > > + { { { { NULL, 0 } } } }
> >
> > This define is way ugly and instead of making superficial changes, you
> > should try to eliminate it.
> >
> > People look at warnings as a bad thing but they are actually a
> > valuable resource which call attention to bad code. By making this
> > change you're kind of wasting the warning. The bad code is still
> > there, it's just swept under the rug but like a dead mouse carcass
> > it's still stinking up the living room. We should leave the warning
> > there until it irritates someone enough to fix it properly.
>
> Tracking down the offending initializer was definitely a pain.
>
> Compound literals with designated initializers would make this macro
> (and a number of others) easier to understand and more type-safe:
>
> #define IA_CSS_DEFAULT_ISP_MEM_PARAMS \
> - { { { { 0, 0 } } } }
> + (struct ia_css_isp_param_host_segments) { \
> + .params = { { \
> + (struct ia_css_host_data) { \
> + .address = NULL, \
> + .size = 0 \
> + } \
> + } } \
> + }
Using designated initializers is good, yes. Can't we just use an
empty initializer since this is all zeroed memory anyway?
(struct ia_css_isp_param_host_segments) { }
I haven't tried it.
>
> Unfortunately this default value is one end of a chain of default values
Yeah. A really long chain...
> used to initialize members of default values of enclosing structs where
> the outermost values are used to initialize some static variables:
>
> static enum ia_css_err
> init_pipe_defaults(enum ia_css_pipe_mode mode,
> struct ia_css_pipe *pipe,
> bool copy_pipe)
> {
> static struct ia_css_pipe default_pipe = IA_CSS_DEFAULT_PIPE;
> static struct ia_css_preview_settings prev =
> IA_CSS_DEFAULT_PREVIEW_SETTINGS;
> static struct ia_css_capture_settings capt =
> IA_CSS_DEFAULT_CAPTURE_SETTINGS;
> static struct ia_css_video_settings video =
> IA_CSS_DEFAULT_VIDEO_SETTINGS;
> static struct ia_css_yuvpp_settings yuvpp =
> IA_CSS_DEFAULT_YUVPP_SETTINGS;
>
> if (pipe == NULL) {
> IA_CSS_ERROR("NULL pipe parameter");
> return IA_CSS_ERR_INVALID_ARGUMENTS;
> }
>
> /* Initialize pipe to pre-defined defaults */
> *pipe = default_pipe;
>
> /* TODO: JB should not be needed, but temporary backward reference */
> switch (mode) {
> case IA_CSS_PIPE_MODE_PREVIEW:
> pipe->mode = IA_CSS_PIPE_ID_PREVIEW;
> pipe->pipe_settings.preview = prev;
> break;
> case IA_CSS_PIPE_MODE_CAPTURE:
> if (copy_pipe) {
> pipe->mode = IA_CSS_PIPE_ID_COPY;
> } else {
> pipe->mode = IA_CSS_PIPE_ID_CAPTURE;
> }
> pipe->pipe_settings.capture = capt;
> break;
> case IA_CSS_PIPE_MODE_VIDEO:
> pipe->mode = IA_CSS_PIPE_ID_VIDEO;
> pipe->pipe_settings.video = video;
> break;
> case IA_CSS_PIPE_MODE_ACC:
> pipe->mode = IA_CSS_PIPE_ID_ACC;
> break;
> case IA_CSS_PIPE_MODE_COPY:
> pipe->mode = IA_CSS_PIPE_ID_CAPTURE;
> break;
> case IA_CSS_PIPE_MODE_YUVPP:
> pipe->mode = IA_CSS_PIPE_ID_YUVPP;
> pipe->pipe_settings.yuvpp = yuvpp;
> break;
> default:
> return IA_CSS_ERR_INVALID_ARGUMENTS;
> }
>
> return IA_CSS_SUCCESS;
> }
>
> and GCC's limited support for using compound literals to initialize
> static variables doesn't stretch this far.
>
> I'm not convinced, however, that those variables actually achieve very
> much. If I change the code to assign the defaults directly, the problem
> goes away:
>
> diff --git a/drivers/staging/media/atomisp/pci/atomisp2/css2400/sh_css.c
> b/drivers/staging/media/atomisp/pci/atomisp2/css2400/sh_css.c
> index f92b6a9f77eb..671b2c732a46 100644
> --- a/drivers/staging/media/atomisp/pci/atomisp2/css2400/sh_css.c
> +++ b/drivers/staging/media/atomisp/pci/atomisp2/css2400/sh_css.c
> @@ -2291,25 +2291,19 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
> struct ia_css_pipe *pipe,
> bool copy_pipe)
> {
> - static struct ia_css_pipe default_pipe = IA_CSS_DEFAULT_PIPE;
> - static struct ia_css_preview_settings prev =
> IA_CSS_DEFAULT_PREVIEW_SETTINGS;
> - static struct ia_css_capture_settings capt =
> IA_CSS_DEFAULT_CAPTURE_SETTINGS;
> - static struct ia_css_video_settings video =
> IA_CSS_DEFAULT_VIDEO_SETTINGS;
> - static struct ia_css_yuvpp_settings yuvpp =
> IA_CSS_DEFAULT_YUVPP_SETTINGS;
> -
> if (pipe == NULL) {
> IA_CSS_ERROR("NULL pipe parameter");
> return IA_CSS_ERR_INVALID_ARGUMENTS;
> }
>
> /* Initialize pipe to pre-defined defaults */
> - *pipe = default_pipe;
> + *pipe = IA_CSS_DEFAULT_PIPE;
>
> /* TODO: JB should not be needed, but temporary backward reference */
> switch (mode) {
> case IA_CSS_PIPE_MODE_PREVIEW:
> pipe->mode = IA_CSS_PIPE_ID_PREVIEW;
> - pipe->pipe_settings.preview = prev;
> + pipe->pipe_settings.preview =
> IA_CSS_DEFAULT_PREVIEW_SETTINGS;
> break;
> case IA_CSS_PIPE_MODE_CAPTURE:
> if (copy_pipe) {
> @@ -2317,11 +2311,11 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
> } else {
> pipe->mode = IA_CSS_PIPE_ID_CAPTURE;
> }
> - pipe->pipe_settings.capture = capt;
> + pipe->pipe_settings.capture =
> IA_CSS_DEFAULT_CAPTURE_SETTINGS;
> break;
> case IA_CSS_PIPE_MODE_VIDEO:
> pipe->mode = IA_CSS_PIPE_ID_VIDEO;
> - pipe->pipe_settings.video = video;
> + pipe->pipe_settings.video = IA_CSS_DEFAULT_VIDEO_SETTINGS;
> break;
> case IA_CSS_PIPE_MODE_ACC:
> pipe->mode = IA_CSS_PIPE_ID_ACC;
> @@ -2331,7 +2325,7 @@ init_pipe_defaults(enum ia_css_pipe_mode mode,
> break;
> case IA_CSS_PIPE_MODE_YUVPP:
> pipe->mode = IA_CSS_PIPE_ID_YUVPP;
> - pipe->pipe_settings.yuvpp = yuvpp;
> + pipe->pipe_settings.yuvpp = IA_CSS_DEFAULT_YUVPP_SETTINGS;
> break;
> default:
> return IA_CSS_ERR_INVALID_ARGUMENTS;
>
> Does this seem reasonable or am I barking up the wrong tree?
Yes. Chopping the chain down and deleting as much of this code as
possible seems a good thing.
regards,
dan carpenter
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