On 9/19/2019 10:08 PM, Jani Nikula wrote:
On Wed, 18 Sep 2019, Animesh Manna <animesh.manna@xxxxxxxxx> wrote:
DSB can program large set of data through indexed register write
(opcode 0x9) in one shot. DSB feature can be used for bulk register
programming e.g. gamma lut programming, HDR meta data programming.
v1: initial version.
v2: simplified code by using ALIGN(). (Chris)
v3: ascii table added as code comment. (Shashank)
v4: cosmetic changes done. (Shashank)
Cc: Shashank Sharma <shashank.sharma@xxxxxxxxx>
Cc: Imre Deak <imre.deak@xxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxx>
Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Reviewed-by: Shashank Sharma <shashank.sharma@xxxxxxxxx>
Signed-off-by: Animesh Manna <animesh.manna@xxxxxxxxx>
---
drivers/gpu/drm/i915/display/intel_dsb.c | 66 ++++++++++++++++++++++++
drivers/gpu/drm/i915/display/intel_dsb.h | 8 +++
2 files changed, 74 insertions(+)
diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
index f94cd6dc98b6..2d80e452e284 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.c
+++ b/drivers/gpu/drm/i915/display/intel_dsb.c
@@ -12,8 +12,10 @@
/* DSB opcodes. */
#define DSB_OPCODE_SHIFT 24
#define DSB_OPCODE_MMIO_WRITE 0x1
+#define DSB_OPCODE_INDEXED_WRITE 0x9
#define DSB_BYTE_EN 0xF
#define DSB_BYTE_EN_SHIFT 20
+#define DSB_REG_VALUE_MASK 0xfffff
struct intel_dsb *
intel_dsb_get(struct intel_crtc *crtc)
@@ -86,6 +88,70 @@ void intel_dsb_put(struct intel_dsb *dsb)
}
}
+void intel_dsb_indexed_reg_write(struct intel_dsb *dsb, i915_reg_t reg,
+ u32 val)
+{
+ struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
+ struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
+ u32 *buf = dsb->cmd_buf;
+ u32 reg_val;
+
+ if (!buf) {
+ I915_WRITE(reg, val);
+ return;
+ }
+
+ if (WARN_ON(dsb->free_pos >= DSB_BUF_SIZE)) {
+ DRM_DEBUG_KMS("DSB buffer overflow\n");
+ return;
+ }
+
+ /*
+ * For example the buffer will look like below for 3 dwords for auto
+ * increment register:
+ * +--------------------------------------------------------+
+ * | size = 3 | offset &| value1 | value2 | value3 | zero |
+ * | | opcode | | | | |
+ * +--------------------------------------------------------+
+ * + + + + + + +
+ * 0 4 8 12 16 20 24
+ * Byte
+ *
+ * As every instruction is 8 byte aligned the index of dsb instruction
+ * will start always from even number while dealing with u32 array. If
+ * we are writing odd no of dwords, Zeros will be added in the end for
+ * padding.
+ */
+ reg_val = buf[dsb->ins_start_offset + 1] & DSB_REG_VALUE_MASK;
dsb->ins_start_offset is never reset anywhere.
Imagine you do:
intel_dsb_indexed_reg_write(dsb, FOO, 0);
intel_dsb_indexed_reg_write(dsb, FOO, 0);
intel_dsb_reg_write(dsb, BAR, 0);
intel_dsb_indexed_reg_write(dsb, FOO, 0);
The last one will screw up the previous indexed writes.
BR,
Jani.
+ if (reg_val != i915_mmio_reg_offset(reg)) {
+ /* Every instruction should be 8 byte aligned. */
+ dsb->free_pos = ALIGN(dsb->free_pos, 2);
+
+ dsb->ins_start_offset = dsb->free_pos;
+
Not sure if I got your point correctly, but here is the ins_start_offset
getting reset, with the new free_pos aligned with 2
- Shashank
+ /* Update the size. */
+ buf[dsb->free_pos++] = 1;
+
+ /* Update the opcode and reg. */
+ buf[dsb->free_pos++] = (DSB_OPCODE_INDEXED_WRITE <<
+ DSB_OPCODE_SHIFT) |
+ i915_mmio_reg_offset(reg);
+
+ /* Update the value. */
+ buf[dsb->free_pos++] = val;
+ } else {
+ /* Update the new value. */
+ buf[dsb->free_pos++] = val;
+
+ /* Update the size. */
+ buf[dsb->ins_start_offset]++;
+ }
+
+ /* if number of data words is odd, then the last dword should be 0.*/
+ if (dsb->free_pos & 0x1)
+ buf[dsb->free_pos] = 0;
+}
+
void intel_dsb_reg_write(struct intel_dsb *dsb, i915_reg_t reg, u32 val)
{
struct intel_crtc *crtc = container_of(dsb, typeof(*crtc), dsb);
diff --git a/drivers/gpu/drm/i915/display/intel_dsb.h b/drivers/gpu/drm/i915/display/intel_dsb.h
index 0686d67b34d5..d6ced4422814 100644
--- a/drivers/gpu/drm/i915/display/intel_dsb.h
+++ b/drivers/gpu/drm/i915/display/intel_dsb.h
@@ -30,11 +30,19 @@ struct intel_dsb {
* and help in calculating tail of command buffer.
*/
int free_pos;
+
+ /*
+ * ins_start_offset will help to store start address
+ * of the dsb instuction of auto-increment register.
+ */
+ u32 ins_start_offset;
};
struct intel_dsb *
intel_dsb_get(struct intel_crtc *crtc);
void intel_dsb_put(struct intel_dsb *dsb);
void intel_dsb_reg_write(struct intel_dsb *dsb, i915_reg_t reg, u32 val);
+void intel_dsb_indexed_reg_write(struct intel_dsb *dsb, i915_reg_t reg,
+ u32 val);
#endif
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