> -Original Message-
> From: Intel-gfx On Behalf Of Ville
> Syrjala
> Sent: Friday, December 16, 2022 6:08 AM
> To: intel-gfx@lists.freedesktop.org
> Subject: [Intel-gfx] [PATCH 07/13] drm/i915/dsb: Improve the indexed reg
> write checks
>
> From: Ville Syrjälä
>
> Currently intel_dsb_indexed_reg_write() just assumes the previus
Typo - previous instruction.
> instructions is also an indexed register write, and thus only checks the
> register offset. Make the check more robust by actually checking the
> instruction opcode as well.
>
> Signed-off-by: Ville Syrjälä
With the above minor fix, LGTM.
Reviewed-by: Animesh Manna
> ---
> drivers/gpu/drm/i915/display/intel_dsb.c | 21 ++---
> 1 file changed, 18 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c
> b/drivers/gpu/drm/i915/display/intel_dsb.c
> index fb20d9ee84a4..fcc3f49c5445 100644
> --- a/drivers/gpu/drm/i915/display/intel_dsb.c
> +++ b/drivers/gpu/drm/i915/display/intel_dsb.c
> @@ -102,6 +102,23 @@ static void intel_dsb_emit(struct intel_dsb *dsb, u32
> ldw, u32 udw)
> buf[dsb->free_pos++] = udw;
> }
>
> +static bool intel_dsb_prev_ins_is_write(struct intel_dsb *dsb,
> + u32 opcode, i915_reg_t reg)
> +{
> + const u32 *buf = dsb->cmd_buf;
> + u32 prev_opcode, prev_reg;
> +
> + prev_opcode = buf[dsb->ins_start_offset + 1] >>
> DSB_OPCODE_SHIFT;
> + prev_reg = buf[dsb->ins_start_offset + 1] & DSB_REG_VALUE_MASK;
> +
> + return prev_opcode == opcode && prev_reg ==
> i915_mmio_reg_offset(reg);
> +}
> +
> +static bool intel_dsb_prev_ins_is_indexed_write(struct intel_dsb *dsb,
> +i915_reg_t reg) {
> + return intel_dsb_prev_ins_is_write(dsb,
> DSB_OPCODE_INDEXED_WRITE,
> +reg); }
> +
> /**
> * intel_dsb_indexed_reg_write() -Write to the DSB context for auto
> * increment register.
> @@ -119,7 +136,6 @@ void intel_dsb_indexed_reg_write(struct intel_dsb
> *dsb,
>i915_reg_t reg, u32 val)
> {
> u32 *buf = dsb->cmd_buf;
> - u32 reg_val;
>
> if (!assert_dsb_has_room(dsb))
> return;
> @@ -140,8 +156,7 @@ void intel_dsb_indexed_reg_write(struct intel_dsb
> *dsb,
>* 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;
> - if (reg_val != i915_mmio_reg_offset(reg)) {
> + if (!intel_dsb_prev_ins_is_indexed_write(dsb, reg)) {
> /* Every instruction should be 8 byte aligned. */
> dsb->free_pos = ALIGN(dsb->free_pos, 2);
>
> --
> 2.37.4
