On 06/04/2023 02:34, Abhinav Kumar wrote:
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.
I'd say, name we can name that dsc_bpp or compressed_bpp instead of just bpp, this way showing that it is a compressed pclk. But please don't complicate the math.
+} ++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_ */
-- With best wishes Dmitry
