| Message ID | 20210909135838.v4.3.I4a672175ba1894294d91d3dbd51da11a8239cf4a@changeid (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | eDP: Support probing eDP panels dynamically instead of hardcoding | expand |
On Thu, 09 Sep 2021, Douglas Anderson <dianders@chromium.org> wrote: > EDIDs have 32-bits worth of data which is intended to be used to > uniquely identify the make/model of a panel. This has historically > been used only internally in the EDID processing code to identify > quirks with panels. > > We'd like to use this panel ID in panel drivers to identify which > panel is hooked up and from that information figure out power sequence > timings. Let's expose this information from the EDID code and also > allow it to be accessed early, before a connector has been created. > > To make matching in the panel drivers code easier, we'll return the > panel ID as a 32-bit value. We'll provide some functions for > converting this value back and forth to something more human readable. > > Signed-off-by: Douglas Anderson <dianders@chromium.org> > Acked-by: Sam Ravnborg <sam@ravnborg.org> Reviewed-by: Jani Nikula <jani.nikula@intel.com> > --- > > Changes in v4: > - Don't refer to "panel-simple" in commit message. > - decode_edid_id() => drm_edid_decode_panel_id() > - drm_do_get_edid_blk0() => drm_do_get_edid_base_block() > - drm_get_panel_id() => drm_edid_get_panel_id() > - encode_edid_id() => drm_edid_encode_panel_id() > - split panel id extraction out to its own function. > > Changes in v3: > - Decode hex product ID w/ same endianness as everyone else. > > drivers/gpu/drm/drm_edid.c | 67 ++++++++++++++++++++++++++++++++++++++ > include/drm/drm_edid.h | 47 ++++++++++++++++++++++++++ > 2 files changed, 114 insertions(+) > > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c > index 520fe1391769..f84e0dd264f4 100644 > --- a/drivers/gpu/drm/drm_edid.c > +++ b/drivers/gpu/drm/drm_edid.c > @@ -2087,6 +2087,73 @@ struct edid *drm_get_edid(struct drm_connector *connector, > } > EXPORT_SYMBOL(drm_get_edid); > > +static u32 edid_extract_panel_id(const struct edid *edid) > +{ > + /* > + * In theory we could try to de-obfuscate this like edid_get_quirks() > + * does, but it's easier to just deal with a 32-bit number since then > + * it can be compared with "==". > + * > + * NOTE that we deal with endianness differently for the top half > + * of this ID than for the bottom half. The bottom half (the product > + * id) gets decoded as little endian by the EDID_PRODUCT_ID because > + * that's how everyone seems to interpret it. The top half (the mfg_id) > + * gets stored as big endian because that makes > + * drm_edid_encode_panel_id() and drm_edid_decode_panel_id() easier > + * to write (it's easier to extract the ASCII). It doesn't really > + * matter, though, as long as the number here is unique. > + */ > + return (u32)edid->mfg_id[0] << 24 | > + (u32)edid->mfg_id[1] << 16 | > + (u32)EDID_PRODUCT_ID(edid); > +} > + > +/** > + * drm_edid_get_panel_id - Get a panel's ID through DDC > + * @adapter: I2C adapter to use for DDC > + * > + * This function reads the first block of the EDID of a panel and (assuming > + * that the EDID is valid) extracts the ID out of it. The ID is a 32-bit value > + * (16 bits of manufacturer ID and 16 bits of per-manufacturer ID) that's > + * supposed to be different for each different modem of panel. > + * > + * This function is intended to be used during early probing on devices where > + * more than one panel might be present. Because of its intended use it must > + * assume that the EDID of the panel is correct, at least as far as the ID > + * is concerned (in other words, we don't process any overrides here). > + * > + * NOTE: it's expected that this function and drm_do_get_edid() will both > + * be read the EDID, but there is no caching between them. Since we're only > + * reading the first block, hopefully this extra overhead won't be too big. > + * > + * Return: A 32-bit ID that should be different for each make/model of panel. > + * See the functions drm_edid_encode_panel_id() and > + * drm_edid_decode_panel_id() for some details on the structure of this > + * ID. > + */ > + > +u32 drm_edid_get_panel_id(struct i2c_adapter *adapter) > +{ > + struct edid *edid; > + u32 panel_id; > + > + edid = drm_do_get_edid_base_block(drm_do_probe_ddc_edid, adapter, > + NULL, NULL); > + > + /* > + * There are no manufacturer IDs of 0, so if there is a problem reading > + * the EDID then we'll just return 0. > + */ > + if (IS_ERR_OR_NULL(edid)) > + return 0; > + > + panel_id = edid_extract_panel_id(edid); > + kfree(edid); > + > + return panel_id; > +} > +EXPORT_SYMBOL(drm_edid_get_panel_id); > + > /** > * drm_get_edid_switcheroo - get EDID data for a vga_switcheroo output > * @connector: connector we're probing > diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h > index deccfd39e6db..4d17cd04fff7 100644 > --- a/include/drm/drm_edid.h > +++ b/include/drm/drm_edid.h > @@ -508,6 +508,52 @@ static inline u8 drm_eld_get_conn_type(const uint8_t *eld) > return eld[DRM_ELD_SAD_COUNT_CONN_TYPE] & DRM_ELD_CONN_TYPE_MASK; > } > > +/** > + * drm_edid_encode_panel_id - Encode an ID for matching against drm_edid_get_panel_id() > + * @vend_chr_0: First character of the vendor string. > + * @vend_chr_2: Second character of the vendor string. > + * @vend_chr_3: Third character of the vendor string. > + * @product_id: The 16-bit product ID. > + * > + * This is a macro so that it can be calculated at compile time and used > + * as an initializer. > + * > + * For instance: > + * drm_edid_encode_panel_id('B', 'O', 'E', 0x2d08) => 0x09e52d08 > + * > + * Return: a 32-bit ID per panel. > + */ > +#define drm_edid_encode_panel_id(vend_chr_0, vend_chr_1, vend_chr_2, product_id) \ > + ((((u32)(vend_chr_0) - '@') & 0x1f) << 26 | \ > + (((u32)(vend_chr_1) - '@') & 0x1f) << 21 | \ > + (((u32)(vend_chr_2) - '@') & 0x1f) << 16 | \ > + ((product_id) & 0xffff)) > + > +/** > + * drm_edid_decode_panel_id - Decode a panel ID from drm_edid_encode_panel_id() > + * @panel_id: The panel ID to decode. > + * @vend: A 4-byte buffer to store the 3-letter vendor string plus a '\0' > + * termination > + * @product_id: The product ID will be returned here. > + * > + * For instance, after: > + * drm_edid_decode_panel_id(0x09e52d08, vend, &product_id) > + * These will be true: > + * vend[0] = 'B' > + * vend[1] = 'O' > + * vend[2] = 'E' > + * vend[3] = '\0' > + * product_id = 0x2d08 > + */ > +static inline void drm_edid_decode_panel_id(u32 panel_id, char vend[4], u16 *product_id) > +{ > + *product_id = (u16)(panel_id & 0xffff); > + vend[0] = '@' + ((panel_id >> 26) & 0x1f); > + vend[1] = '@' + ((panel_id >> 21) & 0x1f); > + vend[2] = '@' + ((panel_id >> 16) & 0x1f); > + vend[3] = '\0'; > +} > + > bool drm_probe_ddc(struct i2c_adapter *adapter); > struct edid *drm_do_get_edid(struct drm_connector *connector, > int (*get_edid_block)(void *data, u8 *buf, unsigned int block, > @@ -515,6 +561,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector, > void *data); > struct edid *drm_get_edid(struct drm_connector *connector, > struct i2c_adapter *adapter); > +u32 drm_edid_get_panel_id(struct i2c_adapter *adapter); > struct edid *drm_get_edid_switcheroo(struct drm_connector *connector, > struct i2c_adapter *adapter); > struct edid *drm_edid_duplicate(const struct edid *edid);
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 520fe1391769..f84e0dd264f4 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -2087,6 +2087,73 @@ struct edid *drm_get_edid(struct drm_connector *connector, } EXPORT_SYMBOL(drm_get_edid); +static u32 edid_extract_panel_id(const struct edid *edid) +{ + /* + * In theory we could try to de-obfuscate this like edid_get_quirks() + * does, but it's easier to just deal with a 32-bit number since then + * it can be compared with "==". + * + * NOTE that we deal with endianness differently for the top half + * of this ID than for the bottom half. The bottom half (the product + * id) gets decoded as little endian by the EDID_PRODUCT_ID because + * that's how everyone seems to interpret it. The top half (the mfg_id) + * gets stored as big endian because that makes + * drm_edid_encode_panel_id() and drm_edid_decode_panel_id() easier + * to write (it's easier to extract the ASCII). It doesn't really + * matter, though, as long as the number here is unique. + */ + return (u32)edid->mfg_id[0] << 24 | + (u32)edid->mfg_id[1] << 16 | + (u32)EDID_PRODUCT_ID(edid); +} + +/** + * drm_edid_get_panel_id - Get a panel's ID through DDC + * @adapter: I2C adapter to use for DDC + * + * This function reads the first block of the EDID of a panel and (assuming + * that the EDID is valid) extracts the ID out of it. The ID is a 32-bit value + * (16 bits of manufacturer ID and 16 bits of per-manufacturer ID) that's + * supposed to be different for each different modem of panel. + * + * This function is intended to be used during early probing on devices where + * more than one panel might be present. Because of its intended use it must + * assume that the EDID of the panel is correct, at least as far as the ID + * is concerned (in other words, we don't process any overrides here). + * + * NOTE: it's expected that this function and drm_do_get_edid() will both + * be read the EDID, but there is no caching between them. Since we're only + * reading the first block, hopefully this extra overhead won't be too big. + * + * Return: A 32-bit ID that should be different for each make/model of panel. + * See the functions drm_edid_encode_panel_id() and + * drm_edid_decode_panel_id() for some details on the structure of this + * ID. + */ + +u32 drm_edid_get_panel_id(struct i2c_adapter *adapter) +{ + struct edid *edid; + u32 panel_id; + + edid = drm_do_get_edid_base_block(drm_do_probe_ddc_edid, adapter, + NULL, NULL); + + /* + * There are no manufacturer IDs of 0, so if there is a problem reading + * the EDID then we'll just return 0. + */ + if (IS_ERR_OR_NULL(edid)) + return 0; + + panel_id = edid_extract_panel_id(edid); + kfree(edid); + + return panel_id; +} +EXPORT_SYMBOL(drm_edid_get_panel_id); + /** * drm_get_edid_switcheroo - get EDID data for a vga_switcheroo output * @connector: connector we're probing diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h index deccfd39e6db..4d17cd04fff7 100644 --- a/include/drm/drm_edid.h +++ b/include/drm/drm_edid.h @@ -508,6 +508,52 @@ static inline u8 drm_eld_get_conn_type(const uint8_t *eld) return eld[DRM_ELD_SAD_COUNT_CONN_TYPE] & DRM_ELD_CONN_TYPE_MASK; } +/** + * drm_edid_encode_panel_id - Encode an ID for matching against drm_edid_get_panel_id() + * @vend_chr_0: First character of the vendor string. + * @vend_chr_2: Second character of the vendor string. + * @vend_chr_3: Third character of the vendor string. + * @product_id: The 16-bit product ID. + * + * This is a macro so that it can be calculated at compile time and used + * as an initializer. + * + * For instance: + * drm_edid_encode_panel_id('B', 'O', 'E', 0x2d08) => 0x09e52d08 + * + * Return: a 32-bit ID per panel. + */ +#define drm_edid_encode_panel_id(vend_chr_0, vend_chr_1, vend_chr_2, product_id) \ + ((((u32)(vend_chr_0) - '@') & 0x1f) << 26 | \ + (((u32)(vend_chr_1) - '@') & 0x1f) << 21 | \ + (((u32)(vend_chr_2) - '@') & 0x1f) << 16 | \ + ((product_id) & 0xffff)) + +/** + * drm_edid_decode_panel_id - Decode a panel ID from drm_edid_encode_panel_id() + * @panel_id: The panel ID to decode. + * @vend: A 4-byte buffer to store the 3-letter vendor string plus a '\0' + * termination + * @product_id: The product ID will be returned here. + * + * For instance, after: + * drm_edid_decode_panel_id(0x09e52d08, vend, &product_id) + * These will be true: + * vend[0] = 'B' + * vend[1] = 'O' + * vend[2] = 'E' + * vend[3] = '\0' + * product_id = 0x2d08 + */ +static inline void drm_edid_decode_panel_id(u32 panel_id, char vend[4], u16 *product_id) +{ + *product_id = (u16)(panel_id & 0xffff); + vend[0] = '@' + ((panel_id >> 26) & 0x1f); + vend[1] = '@' + ((panel_id >> 21) & 0x1f); + vend[2] = '@' + ((panel_id >> 16) & 0x1f); + vend[3] = '\0'; +} + bool drm_probe_ddc(struct i2c_adapter *adapter); struct edid *drm_do_get_edid(struct drm_connector *connector, int (*get_edid_block)(void *data, u8 *buf, unsigned int block, @@ -515,6 +561,7 @@ struct edid *drm_do_get_edid(struct drm_connector *connector, void *data); struct edid *drm_get_edid(struct drm_connector *connector, struct i2c_adapter *adapter); +u32 drm_edid_get_panel_id(struct i2c_adapter *adapter); struct edid *drm_get_edid_switcheroo(struct drm_connector *connector, struct i2c_adapter *adapter); struct edid *drm_edid_duplicate(const struct edid *edid);