Re: [RFC 11/14] drm/i915: Enable MIPI display self refresh mode

Daniel Vetter
2015-06-15T10:30:35Z

On Sat, Jun 13, 2015 at 12:24:57PM +0530, Mohan Marimuthu, Yogesh wrote:
>
>
> On 5/29/2015 10:51 PM, Daniel Vetter wrote:
> >On Fri, May 29, 2015 at 04:07:03PM +0530, Gaurav K Singh wrote:
> >>During enable sequence for MIPI encoder in command mode, enable
> >>MIPI display self-refresh mode bit in Pipe Ctrl reg.
> >>
> >>Signed-off-by: Gaurav K Singh <gaurav.k.singh@intel.com>
> >>Signed-off-by: Yogesh Mohan Marimuthu <yogesh.mohan.marimuthu@intel.com>
> >>Signed-off-by: Shobhit Kumar <shobhit.kumar@intel.com>
> >>---
> >> drivers/gpu/drm/i915/intel_display.c | 15 +++++++++++++++
> >> 1 file changed, 15 insertions(+)
> >>
> >>diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> >>index cab2ac8..fc84313 100644
> >>--- a/drivers/gpu/drm/i915/intel_display.c
> >>+++ b/drivers/gpu/drm/i915/intel_display.c
> >>@@ -44,6 +44,7 @@
> >> #include <drm/drm_plane_helper.h>
> >> #include <drm/drm_rect.h>
> >> #include <linux/dma_remapping.h>
> >>+#include "intel_dsi.h"
> >> /* Primary plane formats supported by all gen */
> >> #define COMMON_PRIMARY_FORMATS \
> >>@@ -2110,6 +2111,8 @@ static void intel_enable_pipe(struct intel_crtc *crtc)
> >> {
> >> struct drm_device *dev = crtc->base.dev;
> >> struct drm_i915_private *dev_priv = dev->dev_private;
> >>+ struct intel_encoder *encoder;
> >>+ struct intel_dsi *intel_dsi;
> >> enum pipe pipe = crtc->pipe;
> >> enum transcoder cpu_transcoder = intel_pipe_to_cpu_transcoder(dev_priv,
> >> pipe);
> >>@@ -2154,6 +2157,18 @@ static void intel_enable_pipe(struct intel_crtc *crtc)
> >> return;
> >> }
> >>+ for_each_encoder_on_crtc(dev, &crtc->base, encoder) {
> >>+ if (encoder->type == INTEL_OUTPUT_DSI) {
> >>+ intel_dsi = enc_to_intel_dsi(&encoder->base);
> >>+ if (intel_dsi && (intel_dsi->operation_mode ==
> >>+ INTEL_DSI_COMMAND_MODE)) {
> >>+ val = val | PIPECONF_MIPI_DSR_ENABLE;
> >>+ I915_WRITE(reg, val);
> >>+ }
> >>+ break;
> >>+ }
> >>+ }
> >When we have these kind of encoder/crtc state depencies we resolve them by
> >adding a bit of state to intel_crtc_state which is set as needed in the
> >encoder's compute_config callback. Then all you need here is
> >
> > if (intel_state->dsi_self_refresh)
> > val |= PIPECONF_MIPI_DSR_ENABLE;
> >
> >Also is that additional write really required?
> >-Daniel
> Yes additional write is required. MIPI_DSR_ENABLE has to be written first
> then followed
> by pipe enable. if MIPI_DSR_ENABLE and pipe enable is done in same write,
> observed
> that the image from pipe is not sent to panel when issued mem write command.
>
> Having a state variable instead of looping through the encoders definitely
> looks good.
> Need to find a place to update the state variable. I will get back on this.

Like I said such state is precomputed in the encoder callbacks, in this
case intel_dsi_compute_config.

Cheers, Daniel
--
Daniel Vetter
Software Engineer, Intel Corporation