On Wed, 2022-06-08 at 16:45 +0800, CK Hu wrote:
Hi, Rex:
On Mon, 2022-05-23 at 12:47 +0200, Guillaume Ranquet wrote:
From: Markus Schneider-Pargmann msp@baylibre.com
This patch adds a DisplayPort driver for the Mediatek mt8195 SoC.
It supports the mt8195, the embedded DisplayPort units. It offers DisplayPort 1.4 with up to 4 lanes.
The driver creates a child device for the phy. The child device will never exist without the parent being active. As they are sharing a register range, the parent passes a regmap pointer to the child so that both can work with the same register range. The phy driver sets device data that is read by the parent to get the phy device that can be used to control the phy properties.
This driver is based on an initial version by Jason-JH.Lin jason-jh.lin@mediatek.com.
Signed-off-by: Markus Schneider-Pargmann msp@baylibre.com Signed-off-by: Guillaume Ranquet granquet@baylibre.com
[snip]
+static bool mtk_dp_set_swing_pre_emphasis(struct mtk_dp *mtk_dp, int lane_num,
int swing_val, intpreemphasis)
The return value is never processed, so let this function to be void.
Regards, CK
Hello CK,
ok, I will drop this. Actually, I change "mtk_dp_write", "mtk_dp_update_bits" and "mtk_dp_bulk_16bit_write" to return void. I don't think we need to handle the issue that we failed to set registers. If we failed to set register, it's because hw is not enable.
Therefore, I drop this and we can reduce many lines of codes.
BRs, Bo-Chen
+{
- int ret;
- u32 lane_shift = lane_num * DP_TX1_VOLT_SWING_SHIFT;
- if (lane_num < 0 || lane_num > 3)
lane_num < 0 would not happen. lane_num > 3 only if device tree max lane is wrong. So I would like to checkout max lane when parsing device tree instead of checking here.
return false;- dev_dbg(mtk_dp->dev,
"link training swing_val= 0x%x, preemphasis = 0x%x\n",swing_val, preemphasis);- ret = mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_SWING_EMP,
swing_val << (DP_TX0_VOLT_SWING_SHIFT- lane_shift),
DP_TX0_VOLT_SWING_MASK << lane_shift);- if (ret)
return ret;- ret = mtk_dp_update_bits(mtk_dp, MTK_DP_TOP_SWING_EMP,
preemphasis << (DP_TX0_PRE_EMPH_SHIFT- lane_shift),
DP_TX0_PRE_EMPH_MASK << lane_shift);- return !ret;
+}