diff options
| author | Hyun Kwon <hyun.kwon@xilinx.com> | 2020-07-29 16:30:45 -0700 |
|---|---|---|
| committer | Hyun Kwon <hyun.kwon@xilinx.com> | 2020-08-01 01:56:10 +0000 |
| commit | 70c8b4b8ab3714fb2d075be22aec05ae9c9a6a09 (patch) | |
| tree | f72aa230f6f051d2760b30645eb0c2c090adc266 | |
| parent | 2d889db7626d2b6d67f402e2478b11f9a49b44e3 (diff) | |
| download | linux-70c8b4b8ab3714fb2d075be22aec05ae9c9a6a09.tar.bz2 | |
drm: xlnx: zynqmp: Use switch - case for link rate downshift
Use switch - case to downshift from the current link rate. It's a small
loop now, so fine to be replaced with switch - case. With a loop, it is
confusing and hard to follow as reported below.
The patch d76271d22694: "drm: xlnx: DRM/KMS driver for Xilinx ZynqMP
DisplayPort Subsystem" from Jul 7, 2018, leads to the following
static checker warning:
drivers/gpu/drm/xlnx/zynqmp_dp.c:594 zynqmp_dp_mode_configure()
error: iterator underflow 'bws' (-1)-2
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Hyun Kwon <hyun.kwon@xilinx.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1596065445-4630-1-git-send-email-hyun.kwon@xilinx.com
| -rw-r--r-- | drivers/gpu/drm/xlnx/zynqmp_dp.c | 29 |
1 files changed, 16 insertions, 13 deletions
diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c index b735072a702d..99158ee67d02 100644 --- a/drivers/gpu/drm/xlnx/zynqmp_dp.c +++ b/drivers/gpu/drm/xlnx/zynqmp_dp.c @@ -567,34 +567,37 @@ static int zynqmp_dp_mode_configure(struct zynqmp_dp *dp, int pclock, u8 current_bw) { int max_rate = dp->link_config.max_rate; - u8 bws[3] = { DP_LINK_BW_1_62, DP_LINK_BW_2_7, DP_LINK_BW_5_4 }; + u8 bw_code; u8 max_lanes = dp->link_config.max_lanes; u8 max_link_rate_code = drm_dp_link_rate_to_bw_code(max_rate); u8 bpp = dp->config.bpp; u8 lane_cnt; - s8 i; - if (current_bw == DP_LINK_BW_1_62) { + /* Downshift from current bandwidth */ + switch (current_bw) { + case DP_LINK_BW_5_4: + bw_code = DP_LINK_BW_2_7; + break; + case DP_LINK_BW_2_7: + bw_code = DP_LINK_BW_1_62; + break; + case DP_LINK_BW_1_62: dev_err(dp->dev, "can't downshift. already lowest link rate\n"); return -EINVAL; - } - - for (i = ARRAY_SIZE(bws) - 1; i >= 0; i--) { - if (current_bw && bws[i] >= current_bw) - continue; - - if (bws[i] <= max_link_rate_code) - break; + default: + /* If not given, start with max supported */ + bw_code = max_link_rate_code; + break; } for (lane_cnt = 1; lane_cnt <= max_lanes; lane_cnt <<= 1) { int bw; u32 rate; - bw = drm_dp_bw_code_to_link_rate(bws[i]); + bw = drm_dp_bw_code_to_link_rate(bw_code); rate = zynqmp_dp_max_rate(bw, lane_cnt, bpp); if (pclock <= rate) { - dp->mode.bw_code = bws[i]; + dp->mode.bw_code = bw_code; dp->mode.lane_cnt = lane_cnt; dp->mode.pclock = pclock; return dp->mode.bw_code; |