On Mon, 30 Jan 2017 15:25:10 -0500, Sean Paul wrote:
On Sun, Jan 29, 2017 at 01:24:33PM +0000, John Keeping wrote:
This clock rate is derived from the PHY PLL, so it should be calculated dynamically. Use the same calculation as the vendor kernel to derive the escape clock speed.
Nit below, but
Reviewed-by: Sean Paul seanpaul@chromium.org
Signed-off-by: John Keeping john@metanate.com Reviewed-by: Chris Zhong zyw@rock-chips.com
v3:
- Improve the commit message a bit
- Add Chris' Reviewed-by
Unchanged in v2
drivers/gpu/drm/rockchip/dw-mipi-dsi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c index 290282e86d16..c2e0ba96e0a0 100644 --- a/drivers/gpu/drm/rockchip/dw-mipi-dsi.c +++ b/drivers/gpu/drm/rockchip/dw-mipi-dsi.c @@ -710,11 +710,13 @@ static void dw_mipi_dsi_disable(struct dw_mipi_dsi *dsi)
static void dw_mipi_dsi_init(struct dw_mipi_dsi *dsi) {
Nit: It would be nice to add a comment to the effect of "You are not meant to understand this, it comes from the vendor kernel"
Actually, I think my commit message was misleading. I think I do understand the calculation, although the TRM is not particularly clear about it. TX_ESC_CLK_DIVISION is described as:
the division factor for the TX_Escape clock source (lanebyteclk). The value 0 and 1 stop the TX_ESC clock generation
Now lanebyteclk is (dsi->lane_mbps >> 3) since lane_mbps is the lane bit clock. The maximum escape mode clock from the MIPI specification is 20MHz, so we end up needing
lanebyteclk / esc_clk_division < 20
thus:
esc_clk_division > lanebyteclk / 20
and we want esc_clk_division >= 2 to avoid disabling the clock generation.
I'll add a comment to this effect.
- u32 esc_clk_division = (dsi->lane_mbps >> 3) / 20 + 1;
- dsi_write(dsi, DSI_PWR_UP, RESET); dsi_write(dsi, DSI_PHY_RSTZ, PHY_DISFORCEPLL | PHY_DISABLECLK | PHY_RSTZ | PHY_SHUTDOWNZ); dsi_write(dsi, DSI_CLKMGR_CFG, TO_CLK_DIVIDSION(10) |
TX_ESC_CLK_DIVIDSION(7));
TX_ESC_CLK_DIVIDSION(esc_clk_division));}
static void dw_mipi_dsi_dpi_config(struct dw_mipi_dsi *dsi,
2.11.0.197.gb556de5.dirty
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