On 4/5/2023 12:26 PM, Dmitry Baryshkov wrote:
On 05/04/2023 03:41, Jessica Zhang wrote:Introduce MSM-specific DSC helper methods, as some calculations are common between DP and DSC. Changes in v2: - Moved files up to msm/ directory - Dropped get_comp_ratio() helper - Used drm_int2fixp() to convert to integers to fp - Style changes to improve readability - Dropped unused bpp variable in msm_dsc_get_dce_bytes_per_line() - Changed msm_dsc_get_slice_per_intf() to a static inline method - Dropped last division step of msm_dsc_get_pclk_per_line() and changed method name accordingly - Changed DSC_BPP macro to drm_dsc_get_bpp_int() helper method - Fixed some math issues caused by passing in incorrect types to drm_fixed methods in get_bytes_per_soft_slice() Changes in v3: - Dropped src_bpp parameter from all methods -- src_bpp can be calculated as dsc->bits_per_component * 3 - Dropped intf_width parameter from get_bytes_per_soft_slice() - Moved dsc->bits_per_component to numerator calculation in get_bytes_per_soft_slice() - Renamed msm_dsc_get_uncompressed_pclk_per_line to *_get_uncompressed_pclk_per_intf() - Removed dsc->slice_width check from msm_dsc_get_uncompressed_pclk_per_intf() - Made get_bytes_per_soft_slice() a public method (this will be called later to help calculate DP pclk params) - Added documentation in comments - Moved extra_eol_bytes math out of msm_dsc_get_eol_byte_num() and renamed msm_dsc_get_eol_byte_num to *_get_bytes_per_intf. Changes in v4: - Changed msm_dsc_get_uncompressed_pclk_per_intf to msm_dsc_get_pclk_per_intf Signed-off-by: Jessica Zhang <quic_jesszhan@xxxxxxxxxxx> --- drivers/gpu/drm/msm/Makefile | 1 + drivers/gpu/drm/msm/msm_dsc_helper.c | 47 ++++++++++++++++++++++++drivers/gpu/drm/msm/msm_dsc_helper.h | 70 ++++++++++++++++++++++++++++++++++++3 files changed, 118 insertions(+) diff --git a/drivers/gpu/drm/msm/Makefile b/drivers/gpu/drm/msm/Makefile index 7274c41228ed..b814fc80e2d5 100644 --- a/drivers/gpu/drm/msm/Makefile +++ b/drivers/gpu/drm/msm/Makefile @@ -94,6 +94,7 @@ msm-y += \ msm_atomic_tracepoints.o \ msm_debugfs.o \ msm_drv.o \ + msm_dsc_helper.o \ msm_fb.o \ msm_fence.o \ msm_gem.o \diff --git a/drivers/gpu/drm/msm/msm_dsc_helper.c b/drivers/gpu/drm/msm/msm_dsc_helper.cnew file mode 100644 index 000000000000..0539221eb09d --- /dev/null +++ b/drivers/gpu/drm/msm/msm_dsc_helper.c @@ -0,0 +1,47 @@ +// SPDX-License-Identifier: GPL-2.0-only +/*+ * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved+ */ + +#include <linux/kernel.h> +#include <linux/errno.h> +#include <drm/drm_fixed.h> + +#include "msm_drv.h" +#include "msm_dsc_helper.h" + +s64 get_bytes_per_soft_slice(struct drm_dsc_config *dsc) +{ + int bpp = msm_dsc_get_bpp_int(dsc); + s64 numerator_fp, denominator_fp;+ s64 comp_ratio_fp = drm_fixp_from_fraction(dsc->bits_per_component * 3, bpp);++ numerator_fp = drm_int2fixp(dsc->slice_width * 3 * dsc->bits_per_component);+ denominator_fp = drm_fixp_mul(comp_ratio_fp, drm_int2fixp(8)); + + return drm_fixp_div(numerator_fp, denominator_fp);If we remove 3 * dsc->bits_per_components from both numerator and denominator, this whole function seems to be as simple as DIV_ROUND_UP(dsc->slice_width * bpp, 8)Or, if you prefer FP math, drm_fixp_from_fraction(dsc->slice_width * bpp, 8).
True and thats not really surprising because bytes_per_soft_slice is eventually (dsc->slice_width * bpp, 8)
I also thought about it after you mentioned that they will cancel out then why was downstream code and our programming guide doing this way.
So i thought a bit more and the reason from what I can see is that its showing that compression ratio was factored into the math while calculating it. If we just go with (dsc->slice_width * bpp, 8), it does not really show that this was actually compressed bytes per slice leading to the earlier confusion that it was uncompressed pclk while it actually was.
+} ++u32 msm_dsc_get_bytes_per_intf(struct drm_dsc_config *dsc, int intf_width)+{ + u32 bytes_per_soft_slice, bytes_per_intf; + s64 bytes_per_soft_slice_fp; + int slice_per_intf = msm_dsc_get_slice_per_intf(dsc, intf_width); + + bytes_per_soft_slice_fp = get_bytes_per_soft_slice(dsc); + bytes_per_soft_slice = drm_fixp2int_ceil(bytes_per_soft_slice_fp); + + bytes_per_intf = bytes_per_soft_slice * slice_per_intf; + + return bytes_per_intf; +} + +int msm_dsc_get_pclk_per_intf(struct drm_dsc_config *dsc) +{ + s64 data_width; + + data_width = drm_fixp_mul(drm_int2fixp(dsc->slice_count), + get_bytes_per_soft_slice(dsc));And this is then DIV_ROUND_UP(dsc->slice_width * dsc->slice_count * bpp, 8)+ + return drm_fixp2int_ceil(data_width); +}diff --git a/drivers/gpu/drm/msm/msm_dsc_helper.h b/drivers/gpu/drm/msm/msm_dsc_helper.hnew file mode 100644 index 000000000000..31116a31090f --- /dev/null +++ b/drivers/gpu/drm/msm/msm_dsc_helper.h @@ -0,0 +1,70 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/*+ * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved+ */ + +#ifndef MSM_DSC_HELPER_H_ +#define MSM_DSC_HELPER_H_ + +#include <drm/display/drm_dsc_helper.h> +#include <drm/drm_modes.h> + +/*+ * Helper methods for MSM specific DSC calculations that are common between timing engine,+ * DSI, and DP. + */ + +/** + * msm_dsc_get_bpp_int - get bits per pixel integer value + * @dsc: Pointer to drm dsc config struct + */ +static inline int msm_dsc_get_bpp_int(struct drm_dsc_config *dsc) +{ + WARN_ON_ONCE(dsc->bits_per_pixel & 0xf); + return dsc->bits_per_pixel >> 4; +} + +/** + * msm_dsc_get_slice_per_intf - get number of slices per interface + * @dsc: Pointer to drm dsc config struct + * @intf_width: interface width + */+static inline int msm_dsc_get_slice_per_intf(struct drm_dsc_config *dsc, int intf_width)+{ + return DIV_ROUND_UP(intf_width, dsc->slice_width); +} + +/**+ * msm_dsc_get_dce_bytes_per_line - get bytes per line to help calculate data width+ * when configuring the timing engine + * @dsc: Pointer to drm dsc config struct + * @intf_width: interface width + */+static inline u32 msm_dsc_get_dce_bytes_per_line(struct drm_dsc_config *dsc, int intf_width)+{ + return DIV_ROUND_UP(msm_dsc_get_bpp_int(dsc) * intf_width, 8); +} + +/** + * get_bytes_per_soft_slice - get size of each soft slice for dsc + * @dsc: Pointer to drm dsc config struct + */ +s64 get_bytes_per_soft_slice(struct drm_dsc_config *dsc); + +/** + * msm_dsc_get_bytes_per_intf - get total bytes per interface + * @dsc: Pointer to drm dsc config struct + * @intf_width: interface width + */+u32 msm_dsc_get_bytes_per_intf(struct drm_dsc_config *dsc, int intf_width);+ +/** + * msm_dsc_get_pclk_per_intf - Calculate pclk per interface. + * @dsc: Pointer to drm dsc config struct + *+ * Note: This value will then be passed along to DSI and DP for some more + * calculations. This is because DSI and DP divide the pclk_per_intf value+ * by different values depending on if widebus is enabled. + */ +int msm_dsc_get_pclk_per_intf(struct drm_dsc_config *dsc);empty line, please+#endif /* MSM_DSC_HELPER_H_ */
