On Thu, Feb 02, 2017 at 11:08:22AM +0530, Sharma, Shashank wrote: > Regards > > Shashank > > > On 2/1/2017 10:02 PM, Thierry Reding wrote: > > On Wed, Feb 01, 2017 at 06:14:39PM +0530, Shashank Sharma wrote: > > > HDMI 2.0 spec mandates scrambling for modes with pixel clock higher > > > than 340Mhz. This patch adds few new functions in drm layer for > > > core drivers to enable/disable scrambling. > > > > > > This patch adds: > > > - A function to detect scrambling support parsing HF-VSDB > > > - A function to check scrambling status runtime using SCDC read. > > > - Two functions to enable/disable scrambling using SCDC read/write. > > > - Few new bools to reflect scrambling support and status. > > > > > > Signed-off-by: Shashank Sharma <[email protected]> > > > --- > > > drivers/gpu/drm/drm_edid.c | 131 > > > +++++++++++++++++++++++++++++++++++++++++++- > > > include/drm/drm_connector.h | 24 ++++++++ > > > include/drm/drm_edid.h | 6 +- > > > 3 files changed, 159 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c > > > index 37902e5..f0d940a 100644 > > > --- a/drivers/gpu/drm/drm_edid.c > > > +++ b/drivers/gpu/drm/drm_edid.c > > > @@ -37,6 +37,7 @@ > > > #include <drm/drm_edid.h> > > > #include <drm/drm_encoder.h> > > > #include <drm/drm_displayid.h> > > > +#include <drm/drm_scdc_helper.h> > > > #define version_greater(edid, maj, min) \ > > > (((edid)->version > (maj)) || \ > > > @@ -3814,6 +3815,132 @@ static void drm_detect_hdmi_scdc(struct > > > drm_connector *connector, > > > } > > > } > > > +static void drm_detect_hdmi_scrambling(struct drm_connector *connector, > > > + const u8 *hf_vsdb) > > > +{ > > > + struct drm_display_info *display = &connector->display_info; > > > + struct drm_hdmi_info *hdmi = &display->hdmi_info; > > > + > > > + /* > > > + * All HDMI 2.0 monitors must support scrambling at rates > 340M. > > In comments below you use Mhz as the abbreviations. This should be > > consistent. Also I think "MHz" is actually the correct spelling. > Agree. > > > + * And as per the spec, three factors confirm this: > > > + * * Availability of a HF-VSDB block in EDID (check) > > > + * * Non zero Max_TMDS_Char_Rate filed in HF-VSDB > > > + * * SCDC support available > > > + * Lets check it out. > > > + */ > > > + > > > + if (hf_vsdb[5]) { > > > + display->max_tmds_clock = hf_vsdb[5] * 5000; > > > + DRM_DEBUG_KMS("HF-VSDB: max TMDS clock %d kHz\n", > > > + display->max_tmds_clock); > > > + > > > + if (hdmi->scdc_supported) { > > > + hdmi->scr_info.supported = true; > > > + > > > + /* Few sinks support scrambling for cloks < 340M */ > > > + if ((hf_vsdb[6] & 0x8)) > > > + hdmi->scr_info.low_clocks = true; > > > + } > > > + } > > > +} > > > + > > > +/** > > > + * drm_check_scrambling_status - what is status of scrambling? > > > + * @adapter: i2c adapter for SCDC channel > > "I2C", same in other parts of this patch. > Got it. > > > + * > > > + * Read the scrambler status over SCDC channel, and check the > > > + * scrambling status. > > > + * > > > + * Return: True if the scrambling is enabled, false otherwise. > > I think the rest of DRM/KMS kerneldoc tries to use "Returns:\n" as a > > standard way to document return values. > Ok. > > > + */ > > > + > > > +bool drm_check_scrambling_status(struct i2c_adapter *adapter) > > Maybe use a drm_scdc_*() prefix for this to make it more consistent with > > other SCDC API. > > > > While at it, would this not be better located in drm_scdc.c along with > > the other helpers? drm_edid.c is more focussed on the parsing aspects of > > all things EDID. > Yeah, the same is mentioned by Ville too, will do that. > > > +{ > > > + u8 status; > > > + > > > + if (drm_scdc_readb(adapter, SCDC_SCRAMBLER_STATUS, &status) < 0) { > > How about storing the error code... > > > > > + DRM_ERROR("Failed to read scrambling status\n"); > > ... and making it part of the error message? Sometimes its useful to > > know what exact error triggered this because it helps narrowing down > > where things went wrong. > Agree, in fact while debugging and testing this patch series, I had to print > it explicitly. > > > > > + return false; > > > + } > > > + > > > + status &= SCDC_SCRAMBLING_STATUS; > > > + return status != 0; > > Maybe make this a single line: > > > > return (status & SCDC_SCRAMBLING_STATUS) != 0; > Got it. > > > > > +} > > > + > > > +/** > > > + * drm_enable_scrambling - enable scrambling > > > + * @connector: target drm_connector > > "target DRM connector"? > Got it. > > > + * @adapter: i2c adapter for SCDC channel > > > + * @force: enable scrambling, even if its already enabled > > > + * > > > + * Write the TMDS config over SCDC channel, and enable scrambling > > > + * Return: True if scrambling is successfully enabled, false otherwise. > > > + */ > > > + > > > +bool drm_enable_scrambling(struct drm_connector *connector, > > > + struct i2c_adapter *adapter, bool force) > > I think I'd move this to drm_scdc.c as well because it primarily > > operates on SCDC. If you do so, might be worth making adapter the first > > argument for consistency with other SCDC API. > Agree, will move it. > > > +{ > > > + u8 config; > > > + struct drm_hdmi_info *hdmi_info = &connector->display_info.hdmi_info; > > > + > > > + if (hdmi_info->scr_info.status && !force) { > > > + DRM_DEBUG_KMS("Scrambling already enabled\n"); > > > + return true; > > > + } > > > + > > > + if (drm_scdc_readb(adapter, SCDC_TMDS_CONFIG, &config) < 0) { > > > + DRM_ERROR("Failed to read tmds config\n"); > > Maybe also print the error code? > Ok. > > > + return false; > > > + } > > > + > > > + config |= SCDC_SCRAMBLING_ENABLE; > > > + > > > + if (drm_scdc_writeb(adapter, SCDC_TMDS_CONFIG, config) < 0) { > > > + DRM_ERROR("Failed to enable scrambling, write error\n"); > > Same here. > Ok > > > + return false; > > > + } > > > + > > > + hdmi_info->scr_info.status = drm_check_scrambling_status(adapter); > > > + return hdmi_info->scr_info.status; > > > +} > > > + > > > +/** > > > + * drm_disable_scrambling - disable scrambling > > > + * @connector: target drm_connector > > > + * @adapter: i2c adapter for SCDC channel > > > + * @force: disable scrambling, even if its already disabled > > > + * > > > + * Write the TMDS config over SCDC channel, and disable scrambling > > > + * Return: True if scrambling is successfully disabled, false otherwise. > > > + */ > > > +bool drm_disable_scrambling(struct drm_connector *connector, > > > + struct i2c_adapter *adapter, bool force) > > > +{ > > > + u8 config; > > > + struct drm_hdmi_info *hdmi_info = &connector->display_info.hdmi_info; > > > + > > > + if (!hdmi_info->scr_info.status && !force) { > > > + DRM_DEBUG_KMS("Scrambling already disabled\n"); > > > + return true; > > > + } > > > + > > > + if (drm_scdc_readb(adapter, SCDC_TMDS_CONFIG, &config) < 0) { > > > + DRM_ERROR("Failed to read tmds config\n"); > > > + return false; > > > + } > > > + > > > + config &= ~SCDC_SCRAMBLING_ENABLE; > > > + > > > + if (drm_scdc_writeb(adapter, SCDC_TMDS_CONFIG, config) < 0) { > > > + DRM_ERROR("Failed to enable scrambling, write error\n"); > > > + return false; > > > + } > > > + > > > + hdmi_info->scr_info.status = drm_check_scrambling_status(adapter); > > > + return !hdmi_info->scr_info.status; > > > +} > > Same comments as for drm_enable_scrambling(). > Got it. > > > @@ -3928,8 +4055,10 @@ static void drm_parse_cea_ext(struct drm_connector > > > *connector, > > > if (cea_db_is_hdmi_vsdb(db)) > > > drm_parse_hdmi_vsdb_video(connector, db); > > > - if (cea_db_is_hdmi_forum_vsdb(db)) > > > + if (cea_db_is_hdmi_forum_vsdb(db)) { > > > drm_detect_hdmi_scdc(connector, db); > > > + drm_detect_hdmi_scrambling(connector, db); > > > + } > > > } > > > } > > > diff --git a/include/drm/drm_connector.h b/include/drm/drm_connector.h > > > index 2435598..b9735bd 100644 > > > --- a/include/drm/drm_connector.h > > > +++ b/include/drm/drm_connector.h > > > @@ -90,6 +90,26 @@ enum subpixel_order { > > > }; > > > + > > > +/** > > > + * struct scrambling: sink's scrambling support. > > > + */ > > > +struct scrambling { > > > + /** > > > + * @supported: scrambling supported for rates > 340Mhz. > > I think it's common to separate number and unit by a space, so "340 > > MHz". > Got it. > > > + */ > > > + bool supported; > > > + /** > > > + * @low_clocks: scrambling supported for rates <= 340Mhz. > > > + */ > > > + bool low_clocks; > > Maybe "low_rates" because a clock is technically the source of a signal > > that oscillates at the given rate. > Agree, will change it. > > > + /** > > > + * @status: scrambling enabled/disabled ? > > > + */ > > > + bool status; > > > +}; > > > + > > > + > > > /** > > > * struct drm_hdmi_info - runtime data about the connected sink > > > * > > > @@ -108,6 +128,10 @@ struct drm_hdmi_info { > > > * @scdc_rr: sink is capable of generating scdc read request. > > > */ > > > bool scdc_rr; > > > + /** > > > + * scr_info: sink's scrambling support and capabilities. > > > + */ > > > + struct scrambling scr_info; > > Again, I think I'd drop _info and instead spell out "scrambling" to make > > this easier to remember. > Sure, can be done. > > > > Also I'm wondering why scdc_supported and scdc_rr are not in a structure > > if scrambling info is. Also since scrambling depends on SCDC, would it > > make sense to embed it in a struct drm_hdmi_scdc_info? > My opinion while designing was: > - SCDC rr support is platform specific, and a platform can choose not to > support read_req but just allow > scrambling using scdc read and write, hence kept that separate > - You need to look into this internal structure, only if scdc is supported. > - Also, SCDC registers can be used beyond scrambling too, like for error > detection, and other cases, so I thought > it would be better to keep it independent. > > Does it make sense ?
Yes, I think that makes sense, but it's not what I was trying to say. =)
What I was trying to say is that read request and scrambling are defined
in the SCDC specification, and therefore they require SCDC. That's why I
think the below is a natural representation because it captures the
dependency in a hierarchy:
> > struct drm_hdmi_scdc_scrambling_info {
> > bool supported;
> > bool low_rates;
> > bool status;
> > };
> >
> > struct drm_hdmi_scdc_info {
> > bool supported;
> > bool read_request;
> >
> > struct drm_hdmi_scdc_scrambling_info scrambling;
> > };
I should have added to the above:
struct drm_hdmi_info {
struct drm_hdmi_scdc_info scdc;
};
So when conditionalizing code this allows for a very natural ordering of
the code:
struct drm_display_info *info = ...;
struct drm_hdmi_scdc_info *scdc = &info->hdmi.scdc;
if (scdc->supported) {
...
if (scdc->read_request) {
...
e.g. set up handler for read requests
...
}
...
if (scdc->scrambling.supported) {
if (mode->clock >= 340000 ||
scdc->scrambling.low_rates) {
...
set up scrambling
...;
}
}
...
}
Thierry
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