diff options
Diffstat (limited to 'drivers/gpu/drm/display/drm_dp_helper.c')
| -rw-r--r-- | drivers/gpu/drm/display/drm_dp_helper.c | 136 |
1 files changed, 88 insertions, 48 deletions
diff --git a/drivers/gpu/drm/display/drm_dp_helper.c b/drivers/gpu/drm/display/drm_dp_helper.c index 57828f2b7b5a..385a1bfdb272 100644 --- a/drivers/gpu/drm/display/drm_dp_helper.c +++ b/drivers/gpu/drm/display/drm_dp_helper.c @@ -24,6 +24,7 @@ #include <linux/delay.h> #include <linux/dynamic_debug.h> #include <linux/errno.h> +#include <linux/export.h> #include <linux/i2c.h> #include <linux/init.h> #include <linux/iopoll.h> @@ -692,6 +693,34 @@ void drm_dp_dpcd_set_powered(struct drm_dp_aux *aux, bool powered) EXPORT_SYMBOL(drm_dp_dpcd_set_powered); /** + * drm_dp_dpcd_set_probe() - Set whether a probing before DPCD access is done + * @aux: DisplayPort AUX channel + * @enable: Enable the probing if required + */ +void drm_dp_dpcd_set_probe(struct drm_dp_aux *aux, bool enable) +{ + WRITE_ONCE(aux->dpcd_probe_disabled, !enable); +} +EXPORT_SYMBOL(drm_dp_dpcd_set_probe); + +static bool dpcd_access_needs_probe(struct drm_dp_aux *aux) +{ + /* + * HP ZR24w corrupts the first DPCD access after entering power save + * mode. Eg. on a read, the entire buffer will be filled with the same + * byte. Do a throw away read to avoid corrupting anything we care + * about. Afterwards things will work correctly until the monitor + * gets woken up and subsequently re-enters power save mode. + * + * The user pressing any button on the monitor is enough to wake it + * up, so there is no particularly good place to do the workaround. + * We just have to do it before any DPCD access and hope that the + * monitor doesn't power down exactly after the throw away read. + */ + return !aux->is_remote && !READ_ONCE(aux->dpcd_probe_disabled); +} + +/** * drm_dp_dpcd_read() - read a series of bytes from the DPCD * @aux: DisplayPort AUX channel (SST or MST) * @offset: address of the (first) register to read @@ -712,20 +741,8 @@ ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset, { int ret; - /* - * HP ZR24w corrupts the first DPCD access after entering power save - * mode. Eg. on a read, the entire buffer will be filled with the same - * byte. Do a throw away read to avoid corrupting anything we care - * about. Afterwards things will work correctly until the monitor - * gets woken up and subsequently re-enters power save mode. - * - * The user pressing any button on the monitor is enough to wake it - * up, so there is no particularly good place to do the workaround. - * We just have to do it before any DPCD access and hope that the - * monitor doesn't power down exactly after the throw away read. - */ - if (!aux->is_remote) { - ret = drm_dp_dpcd_probe(aux, DP_DPCD_REV); + if (dpcd_access_needs_probe(aux)) { + ret = drm_dp_dpcd_probe(aux, DP_LANE0_1_STATUS); if (ret < 0) return ret; } @@ -2137,14 +2154,17 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, for (i = 0; i < num; i++) { msg.address = msgs[i].addr; - drm_dp_i2c_msg_set_request(&msg, &msgs[i]); - /* Send a bare address packet to start the transaction. - * Zero sized messages specify an address only (bare - * address) transaction. - */ - msg.buffer = NULL; - msg.size = 0; - err = drm_dp_i2c_do_msg(aux, &msg); + + if (!aux->no_zero_sized) { + drm_dp_i2c_msg_set_request(&msg, &msgs[i]); + /* Send a bare address packet to start the transaction. + * Zero sized messages specify an address only (bare + * address) transaction. + */ + msg.buffer = NULL; + msg.size = 0; + err = drm_dp_i2c_do_msg(aux, &msg); + } /* * Reset msg.request in case in case it got @@ -2163,6 +2183,8 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, msg.buffer = msgs[i].buf + j; msg.size = min(transfer_size, msgs[i].len - j); + if (j + msg.size == msgs[i].len && aux->no_zero_sized) + msg.request &= ~DP_AUX_I2C_MOT; err = drm_dp_i2c_drain_msg(aux, &msg); /* @@ -2180,15 +2202,17 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs, } if (err >= 0) err = num; - /* Send a bare address packet to close out the transaction. - * Zero sized messages specify an address only (bare - * address) transaction. - */ - msg.request &= ~DP_AUX_I2C_MOT; - msg.buffer = NULL; - msg.size = 0; - (void)drm_dp_i2c_do_msg(aux, &msg); + if (!aux->no_zero_sized) { + /* Send a bare address packet to close out the transaction. + * Zero sized messages specify an address only (bare + * address) transaction. + */ + msg.request &= ~DP_AUX_I2C_MOT; + msg.buffer = NULL; + msg.size = 0; + (void)drm_dp_i2c_do_msg(aux, &msg); + } return err; } @@ -4393,8 +4417,9 @@ EXPORT_SYMBOL(drm_panel_dp_aux_backlight); #endif /* See DP Standard v2.1 2.6.4.4.1.1, 2.8.4.4, 2.8.7 */ -static int drm_dp_link_symbol_cycles(int lane_count, int pixels, int bpp_x16, - int symbol_size, bool is_mst) +static int drm_dp_link_data_symbol_cycles(int lane_count, int pixels, + int bpp_x16, int symbol_size, + bool is_mst) { int cycles = DIV_ROUND_UP(pixels * bpp_x16, 16 * symbol_size * lane_count); int align = is_mst ? 4 / lane_count : 1; @@ -4402,22 +4427,42 @@ static int drm_dp_link_symbol_cycles(int lane_count, int pixels, int bpp_x16, return ALIGN(cycles, align); } -static int drm_dp_link_dsc_symbol_cycles(int lane_count, int pixels, int slice_count, - int bpp_x16, int symbol_size, bool is_mst) +/** + * drm_dp_link_symbol_cycles - calculate the link symbol count with/without dsc + * @lane_count: DP link lane count + * @pixels: number of pixels in a scanline + * @dsc_slice_count: number of slices for DSC or '0' for non-DSC + * @bpp_x16: bits per pixel in .4 binary fixed format + * @symbol_size: DP symbol size + * @is_mst: %true for MST and %false for SST + * + * Calculate the link symbol cycles for both DSC (@dsc_slice_count !=0) and + * non-DSC case (@dsc_slice_count == 0) and return the count. + */ +int drm_dp_link_symbol_cycles(int lane_count, int pixels, int dsc_slice_count, + int bpp_x16, int symbol_size, bool is_mst) { + int slice_count = dsc_slice_count ? : 1; int slice_pixels = DIV_ROUND_UP(pixels, slice_count); - int slice_data_cycles = drm_dp_link_symbol_cycles(lane_count, slice_pixels, - bpp_x16, symbol_size, is_mst); - int slice_eoc_cycles = is_mst ? 4 / lane_count : 1; + int slice_data_cycles = drm_dp_link_data_symbol_cycles(lane_count, + slice_pixels, + bpp_x16, + symbol_size, + is_mst); + int slice_eoc_cycles = 0; + + if (dsc_slice_count) + slice_eoc_cycles = is_mst ? 4 / lane_count : 1; return slice_count * (slice_data_cycles + slice_eoc_cycles); } +EXPORT_SYMBOL(drm_dp_link_symbol_cycles); /** * drm_dp_bw_overhead - Calculate the BW overhead of a DP link stream * @lane_count: DP link lane count * @hactive: pixel count of the active period in one scanline of the stream - * @dsc_slice_count: DSC slice count if @flags/DRM_DP_LINK_BW_OVERHEAD_DSC is set + * @dsc_slice_count: number of slices for DSC or '0' for non-DSC * @bpp_x16: bits per pixel in .4 binary fixed point * @flags: DRM_DP_OVERHEAD_x flags * @@ -4431,7 +4476,7 @@ static int drm_dp_link_dsc_symbol_cycles(int lane_count, int pixels, int slice_c * as well as the stream's * - @hactive timing * - @bpp_x16 color depth - * - compression mode (@flags / %DRM_DP_OVERHEAD_DSC). + * - compression mode (@dsc_slice_count != 0) * Note that this overhead doesn't account for the 8b/10b, 128b/132b * channel coding efficiency, for that see * @drm_dp_link_bw_channel_coding_efficiency(). @@ -4486,15 +4531,10 @@ int drm_dp_bw_overhead(int lane_count, int hactive, WARN_ON((flags & DRM_DP_BW_OVERHEAD_UHBR) && (flags & DRM_DP_BW_OVERHEAD_FEC)); - if (flags & DRM_DP_BW_OVERHEAD_DSC) - symbol_cycles = drm_dp_link_dsc_symbol_cycles(lane_count, hactive, - dsc_slice_count, - bpp_x16, symbol_size, - is_mst); - else - symbol_cycles = drm_dp_link_symbol_cycles(lane_count, hactive, - bpp_x16, symbol_size, - is_mst); + symbol_cycles = drm_dp_link_symbol_cycles(lane_count, hactive, + dsc_slice_count, + bpp_x16, symbol_size, + is_mst); return DIV_ROUND_UP_ULL(mul_u32_u32(symbol_cycles * symbol_size * lane_count, overhead * 16), |