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charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Hi Laurent, Thanks for the comment. On Thu, Jul 30, 2020 at 04:12:46PM -0700, Laurent Pinchart wrote: > Hi Hyun, > > Thank you for the patch. > > On Wed, Jul 29, 2020 at 04:30:45PM -0700, Hyun Kwon wrote: > > 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 > > Signed-off-by: Hyun Kwon > > --- > > v2 > > - Convert the for loop into switch - case > > --- > > --- > > drivers/gpu/drm/xlnx/zynqmp_dp.c | 29 ++++++++++++++++------------- > > 1 file changed, 16 insertions(+), 13 deletions(-) > > > > diff --git a/drivers/gpu/drm/xlnx/zynqmp_dp.c b/drivers/gpu/drm/xlnx/zynqmp_dp.c > > index b735072..5d6adeaa 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 one */ > > Maybe "Downshift from the current bandwidth" ? > > Reviewed-by: Laurent Pinchart > I agree. I'll fix and add the tag. Thanks! -hyun > > + 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; > > -- > Regards, > > Laurent Pinchart _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel