| Message ID | 20230427142934.55435-9-francesco@dolcini.it (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/bridge: tc358768: various fixes on PLL calculation and DSI timings | expand |
On Thu, Apr 27, 2023 at 4:34 PM Francesco Dolcini <francesco@dolcini.it> wrote: > > From: Francesco Dolcini <francesco.dolcini@toradex.com> > > Correct computation of THS_TRAILCNT register. > > This register must be set to a value that ensure that > THS_TRAIL > 60 ns + 4 x UI > and > THS_TRAIL > 8 x UI > and > THS_TRAIL < TEOT > with > TEOT = 105 ns + (12 x UI) > > with the actual value of THS_TRAIL being > > (1 + THS_TRAILCNT) x ByteClk cycle + ((1 to 2) + 2) xHSBYTECLK cycle + > - (PHY output delay) > > with PHY output delay being about > > (8 + (5 to 6)) x MIPIBitClk cycle in the BitClk conversion. > > Fixes: ff1ca6397b1d ("drm/bridge: Add tc358768 driver") > Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com> > --- > drivers/gpu/drm/bridge/tc358768.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c > index 854fc04f08d0..947c7dca567a 100644 > --- a/drivers/gpu/drm/bridge/tc358768.c > +++ b/drivers/gpu/drm/bridge/tc358768.c > @@ -779,9 +779,10 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge) > dev_dbg(priv->dev, "TCLK_POSTCNT: 0x%x\n", val); > tc358768_write(priv, TC358768_TCLK_POSTCNT, val); > > - /* 60ns + 4*UI < THS_PREPARE < 105ns + 12*UI */ > - val = tc358768_ns_to_cnt(60 + tc358768_to_ns(15 * ui_nsk), > - dsibclk_nsk) - 5; > + /* max(60ns + 4*UI, 8*UI) < THS_TRAILCNT < 105ns + 12*UI */ > + raw_val = tc358768_ns_to_cnt(60 + tc358768_to_ns(18 * ui_nsk), > + dsibclk_nsk) - 4; > + val = clamp(raw_val, 0, 15); > dev_dbg(priv->dev, "THS_TRAILCNT: 0x%x\n", val); > tc358768_write(priv, TC358768_THS_TRAILCNT, val); > > -- > 2.25.1 > Reviewed-by: Robert Foss <rfoss@kernel.org>
diff --git a/drivers/gpu/drm/bridge/tc358768.c b/drivers/gpu/drm/bridge/tc358768.c index 854fc04f08d0..947c7dca567a 100644 --- a/drivers/gpu/drm/bridge/tc358768.c +++ b/drivers/gpu/drm/bridge/tc358768.c @@ -779,9 +779,10 @@ static void tc358768_bridge_pre_enable(struct drm_bridge *bridge) dev_dbg(priv->dev, "TCLK_POSTCNT: 0x%x\n", val); tc358768_write(priv, TC358768_TCLK_POSTCNT, val); - /* 60ns + 4*UI < THS_PREPARE < 105ns + 12*UI */ - val = tc358768_ns_to_cnt(60 + tc358768_to_ns(15 * ui_nsk), - dsibclk_nsk) - 5; + /* max(60ns + 4*UI, 8*UI) < THS_TRAILCNT < 105ns + 12*UI */ + raw_val = tc358768_ns_to_cnt(60 + tc358768_to_ns(18 * ui_nsk), + dsibclk_nsk) - 4; + val = clamp(raw_val, 0, 15); dev_dbg(priv->dev, "THS_TRAILCNT: 0x%x\n", val); tc358768_write(priv, TC358768_THS_TRAILCNT, val);