Hi Manjunath, On Tuesday 17 July 2012 10:43:54 Hadli, Manjunath wrote: > On Sun, Jul 15, 2012 at 18:16:25, Laurent Pinchart wrote: > > On Wednesday 11 July 2012 21:09:26 Manjunath Hadli wrote: > > > Add documentation on the Davinci VPFE driver. Document the subdevs, > > > and private IOTCLs the driver implements > > > > > > Signed-off-by: Manjunath Hadli <manjunath.hadli@xxxxxx> > > > Signed-off-by: Lad, Prabhakar <prabhakar.lad@xxxxxx> [snip] > > > +Private IOCTLs > > > +============== > > > + > > > +The Davinci Video processing Front End (VPFE) driver supports standard > > > V4L2 +IOCTLs and controls where possible and practical. Much of the > > > functions provided > > > +by the VPFE, however, does not fall under the standard IOCTLs. > > > + > > > +In general, there is a private ioctl for configuring each of the blocks > > > +containing hardware-dependent functions. > > > + > > > +The following private IOCTLs are supported: > > > + > > > +1: IOCTL: PREV_S_PARAM/PREV_G_PARAM > > > +Description: > > > + Sets/Gets the parameters required by the previewer module > > > +Parameter: > > > + /** > > > + * struct prev_module_param- structure to configure preview modules > > > + * @version: Version of the preview module > > > > Who is responsible for filling this field, the application or the driver ? > > The application is responsible for filling this info. He would enumerate the > capabilities first and set them using S_PARAM/G_PARAM. And what's the point of the application setting the version field ? How does the driver use it ? > > > + * @len: Length of the module config structure > > > + * @module_id: Module id > > > + * @param: pointer to module config parameter. > > > > What is module_id for ? What does param point to ? > > There are a lot of tiny modules in the previewer/resizer which are > enumerated as individual modules. The param points to the parameter set > that the module expects to be set. Why don't you implement something similar to VPFE_CMD_S_CCDC_RAW_PARAMS/VPFE_CMD_G_CCDC_RAW_PARAMS instead ? > > > + */ > > > + struct prev_module_param { > > > + char version[IMP_MAX_NAME_SIZE]; > > > > Is there a need to express the version as a string instead of an integer ? > > It could be integer. It is generally a fixed point num, and easy to read it > as a string than an integer. Can I keep it as a string? Let's first decide whether a version field is needed at all :-) > > > + unsigned short len; > > > + unsigned short module_id; > > > + void *param; > > > + }; > > > + > > > +2: IOCTL: PREV_S_CONFIG/PREV_G_CONFIG > > > +Description: > > > + Sets/Gets the configuration required by the previewer channel > > > +Parameter: > > > + /** > > > + * struct prev_channel_config - structure for configuring the > > > previewer > > > channel > > > + * @len: Length of the user configuration > > > + * @config: pointer to either single shot config or continuous > > > + */ > > > + struct prev_channel_config { > > > + unsigned short len; > > > + void *config; > > > + }; > > > > What's the difference between parameters and configuration ? What does > > config point to ? > > Config is setting which is required for a subdev to function based on what > it is set for (single shot/continuous.) common to all platforms. Parameters > are the settings for individual small sub-ips which might be slightly > different from one platform to another. Config points to > prev_single_shot_config or prev_continuous_config currently defined in > linux/dm3656ipipe.h. I think we will move it to a common location. Why don't you implement something similar to VPFE_CMD_S_CCDC_RAW_PARAMS/VPFE_CMD_G_CCDC_RAW_PARAMS here as well (same for the resizer configuration ioctls) ? > > > + > > > +3: IOCTL: PREV_ENUM_CAP > > > +Description: > > > + Queries the modules available in the image processor for preview the > > > + input image. > > > +Parameter: > > > + /** > > > + * struct prev_cap - structure to enumerate capabilities of previewer > > > + * @index: application use this to iterate over the available modules > > > + * @version: version of the preview module > > > + * @module_id: module id > > > + * @control: control operation allowed in continuous mode? 1 - > > > allowed, 0 > > > - not allowed > > > + * @path: path on which the module is sitting > > > + * @module_name: module name > > > + */ > > > + struct prev_cap { > > > + unsigned short index; > > > + char version[IMP_MAX_NAME_SIZE]; > > > + unsigned short module_id; > > > + char control; > > > + enum imp_data_paths path; > > > + char module_name[IMP_MAX_NAME_SIZE]; > > > + }; > > > > Enumerating internal modules is exactly what the MC API was designed for. > > Why do you reimplement that using private ioctls ? > > The number of these sub-Ips are quite a few in DM365 and Dm355, having a lot > of them In a way that may be bewildering to the end-user to be able to > connect them quickly and properly. But overall, these are nothing but > exposed subips of what we call as CCDC,Previewer and Resizer.It Made a lot > of logical sense to keep it that way, give a default configuration for > everything, and if at all the user wants the fine grain config control, be > able to give (mainly for the configurations- not so much for connections). > In most of the cases the param IOTCLs are only used for fine-tuning the > image and not expected to be used as a regular flow of a normal > application. I do not think there could be any justification for making all > these nitty gritty which keep changing for each IPs as part of regular V4L2 > IOCTLs. In future, if there is a common theme that emerges, we could > definitely relook into this. I totally agree with you on this, the tiny sub-blocks should not be exposed as through the MC API. However, I would go one step further : I wouldn't expose them through a private ioctl either. What would a userspace application do with this information that it couldn't do with just the entity name and its revision number ? [snip] > > > +5: IOCTL: VPFE_CMD_S_CCDC_RAW_PARAMS/VPFE_CMD_G_CCDC_RAW_PARAMS > > > +Description: > > > + Sets/Gets the CCDC parameter > > > +Parameter: > > > + /** > > > + * struct ccdc_config_params_raw - structure for configuring ccdc > > > params > > > + * @linearize: linearization parameters for image sensor data input > > > + * @df_csc: data formatter or CSC > > > + * @dfc: defect Pixel Correction (DFC) configuration > > > + * @bclamp: Black/Digital Clamp configuration > > > + * @gain_offset: Gain, offset adjustments > > > > Can't you use subdev V4L2 controls for gains ? > > In that case only gain has to be taken out as a generic IOCTL. Since that is > is The parameter which could be taken out of this big structure That's correct. > > > + * @culling: Culling > > > + * @pred: predictor for DPCM compression > > > + * @horz_offset: horizontal offset for Gain/LSC/DFC > > > + * @vert_offset: vertical offset for Gain/LSC/DFC > > > + * @col_pat_field0: color pattern for field 0 > > > + * @col_pat_field1: color pattern for field 1 > > > > Shouldn't color patterns be computed automatically by the driver based on > > the media bus pixel code ? > > OK. > > > > + * @data_size: data size from 8 to 16 bits > > > + * @data_shift: data shift applied before storing to SDRAM > > > > Ditto, this should probably be computed automatically. > > Do you want to define new MBUS formats for these? The media bus format contains information about the data width, so I think those fields are redundant. > > > + * @test_pat_gen: enable input test pattern generation > > > > You could use a subdev V4L2 control for that. > > Ok. > > > > + */ > > > + struct ccdc_config_params_raw { > > > + struct ccdc_linearize linearize; > > > + struct ccdc_df_csc df_csc; > > > + struct ccdc_dfc dfc; > > > + struct ccdc_black_clamp bclamp; > > > + struct ccdc_gain_offsets_adj gain_offset; > > > + struct ccdc_cul culling; > > > + enum ccdc_dpcm_predictor pred; > > > + unsigned short horz_offset; > > > + unsigned short vert_offset; > > > + struct ccdc_col_pat col_pat_field0; > > > + struct ccdc_col_pat col_pat_field1; > > > + enum ccdc_data_size data_size; > > > + enum ccdc_datasft data_shift; > > > + unsigned char test_pat_gen; > > > + }; > > > + [snip] > > > +7: IOCTL: AF_GET_STAT > > > +Description: > > > + Copy the entire statistics located in application buffer > > > + to user space from the AF engine > > > +Parameter: > > > + /** > > > + * struct af_statdata - structure to get statistics from AF engine > > > + * @buffer: pointer to buffer > > > + * @buf_length: length of buffer > > > + */ > > > + struct af_statdata { > > > + void *buffer; > > > + int buf_length; > > > + }; > > > > The OMAP3 ISP driver also needs to export statistics data to userspace. We > > should design a common API here. > > Sure we can take it up sometime later. [snip] > > > +9: IOCTL: AEW_GET_STAT > > > +Description: > > > + Copy the entire statistics located in application buffer > > > + to user space from the AEW engine > > > +Parameter: > > > + /** > > > + * struct aew_statdata - structure to get statistics from AEW engine > > > + * @buffer: pointer to buffer > > > + * @buf_length: length of buffer > > > + */ > > > + struct aew_statdata { > > > + void *buffer; > > > + int buf_length; > > > + }; > > > > Same comment as for AF_GET_STAT. > > Yes, we can discuss about it to make it common. I would prefer we get this > driver in and make amends when you are doing it for OMAP. OK, but then please start a discussion on the mailing list about this topic (CC'ing David Cohen as he might be interested). -- Regards, Laurent Pinchart -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html