Re: [PATCH] Revert "drm/xe: Force write completion of MI_STORE_DATA_IMM"

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Thu, 26 Dec 2024 08:23:10 -0800, José Roberto de Souza wrote:
>
> This reverts commit 1460bb1fef9ccf7390af0d74a15252442fd6effd.
>
> In all places the MI_STORE_DATA_IMM are not followed by a read of
> the same memory address in the same batch buffer and the posted writes
> are flushed with PIPE_CONTROL or MI_FLUSH_DW in xe_ring_ops.c functions
> so there is no need to set this register.

As I was saying this commit message should just be:

In all places where MI_STORE_DATA_IMM is used, posted writes are flushed
with PIPE_CONTROL or MI_FLUSH_DW in xe_ring_ops.c functions, so there is no
need to set this register.

So according to me the "are not followed by a read of the same memory
address in the same batch buffer" is incorrect, it will work even without
setting the flag.

Anyway apart from that nit, this is:

Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>

>
> Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
> Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
> Fixes: 1460bb1fef9c ("drm/xe: Force write completion of MI_STORE_DATA_IMM")
> Signed-off-by: José Roberto de Souza <jose.souza@intel.com>
> ---
>  drivers/gpu/drm/xe/instructions/xe_mi_commands.h | 13 ++++++-------
>  drivers/gpu/drm/xe/xe_migrate.c                  | 11 +++--------
>  drivers/gpu/drm/xe/xe_ring_ops.c                 |  6 ++----
>  3 files changed, 11 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/instructions/xe_mi_commands.h b/drivers/gpu/drm/xe/instructions/xe_mi_commands.h
> index f4ee910f09432..10ec2920d31b3 100644
> --- a/drivers/gpu/drm/xe/instructions/xe_mi_commands.h
> +++ b/drivers/gpu/drm/xe/instructions/xe_mi_commands.h
> @@ -33,13 +33,12 @@
>  #define MI_TOPOLOGY_FILTER		__MI_INSTR(0xD)
>  #define MI_FORCE_WAKEUP			__MI_INSTR(0x1D)
>
> -#define MI_STORE_DATA_IMM			__MI_INSTR(0x20)
> -#define   MI_SDI_GGTT				REG_BIT(22)
> -#define   MI_FORCE_WRITE_COMPLETION_CHECK	REG_BIT(10)
> -#define   MI_SDI_LEN_DW				GENMASK(9, 0)
> -#define   MI_SDI_NUM_DW(x)			REG_FIELD_PREP(MI_SDI_LEN_DW, (x) + 3 - 2)
> -#define   MI_SDI_NUM_QW(x)			(REG_FIELD_PREP(MI_SDI_LEN_DW, 2 * (x) + 3 - 2) | \
> -						 REG_BIT(21))
> +#define MI_STORE_DATA_IMM		__MI_INSTR(0x20)
> +#define   MI_SDI_GGTT			REG_BIT(22)
> +#define   MI_SDI_LEN_DW			GENMASK(9, 0)
> +#define   MI_SDI_NUM_DW(x)		REG_FIELD_PREP(MI_SDI_LEN_DW, (x) + 3 - 2)
> +#define   MI_SDI_NUM_QW(x)		(REG_FIELD_PREP(MI_SDI_LEN_DW, 2 * (x) + 3 - 2) | \
> +					 REG_BIT(21))
>
>  #define MI_LOAD_REGISTER_IMM		__MI_INSTR(0x22)
>  #define   MI_LRI_LRM_CS_MMIO		REG_BIT(19)
> diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
> index 8b32fad678782..1b97d90aaddaf 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.c
> +++ b/drivers/gpu/drm/xe/xe_migrate.c
> @@ -581,9 +581,7 @@ static void emit_pte(struct xe_migrate *m,
>	while (ptes) {
>		u32 chunk = min(MAX_PTE_PER_SDI, ptes);
>
> -		bb->cs[bb->len++] = MI_STORE_DATA_IMM |
> -				    MI_FORCE_WRITE_COMPLETION_CHECK |
> -				    MI_SDI_NUM_QW(chunk);
> +		bb->cs[bb->len++] = MI_STORE_DATA_IMM | MI_SDI_NUM_QW(chunk);
>		bb->cs[bb->len++] = ofs;
>		bb->cs[bb->len++] = 0;
>
> @@ -1225,9 +1223,7 @@ static void write_pgtable(struct xe_tile *tile, struct xe_bb *bb, u64 ppgtt_ofs,
>		if (!(bb->len & 1))
>			bb->cs[bb->len++] = MI_NOOP;
>
> -		bb->cs[bb->len++] = MI_STORE_DATA_IMM |
> -				    MI_FORCE_WRITE_COMPLETION_CHECK |
> -				    MI_SDI_NUM_QW(chunk);
> +		bb->cs[bb->len++] = MI_STORE_DATA_IMM | MI_SDI_NUM_QW(chunk);
>		bb->cs[bb->len++] = lower_32_bits(addr);
>		bb->cs[bb->len++] = upper_32_bits(addr);
>		if (pt_op->bind)
> @@ -1392,8 +1388,7 @@ __xe_migrate_update_pgtables(struct xe_migrate *m,
>			u32 idx = 0;
>
>			bb->cs[bb->len++] = MI_STORE_DATA_IMM |
> -					    MI_FORCE_WRITE_COMPLETION_CHECK |
> -					    MI_SDI_NUM_QW(chunk);
> +				MI_SDI_NUM_QW(chunk);
>			bb->cs[bb->len++] = ofs;
>			bb->cs[bb->len++] = 0; /* upper_32_bits */
>
> diff --git a/drivers/gpu/drm/xe/xe_ring_ops.c b/drivers/gpu/drm/xe/xe_ring_ops.c
> index c8ab37fa0d198..9f327f27c0726 100644
> --- a/drivers/gpu/drm/xe/xe_ring_ops.c
> +++ b/drivers/gpu/drm/xe/xe_ring_ops.c
> @@ -72,8 +72,7 @@ static int emit_user_interrupt(u32 *dw, int i)
>
>  static int emit_store_imm_ggtt(u32 addr, u32 value, u32 *dw, int i)
>  {
> -	dw[i++] = MI_STORE_DATA_IMM | MI_SDI_GGTT |
> -		  MI_FORCE_WRITE_COMPLETION_CHECK | MI_SDI_NUM_DW(1);
> +	dw[i++] = MI_STORE_DATA_IMM | MI_SDI_GGTT | MI_SDI_NUM_DW(1);
>	dw[i++] = addr;
>	dw[i++] = 0;
>	dw[i++] = value;
> @@ -163,8 +162,7 @@ static int emit_pipe_invalidate(u32 mask_flags, bool invalidate_tlb, u32 *dw,
>  static int emit_store_imm_ppgtt_posted(u64 addr, u64 value,
>				       u32 *dw, int i)
>  {
> -	dw[i++] = MI_STORE_DATA_IMM | MI_FORCE_WRITE_COMPLETION_CHECK |
> -		  MI_SDI_NUM_QW(1);
> +	dw[i++] = MI_STORE_DATA_IMM | MI_SDI_NUM_QW(1);
>	dw[i++] = lower_32_bits(addr);
>	dw[i++] = upper_32_bits(addr);
>	dw[i++] = lower_32_bits(value);
> --
> 2.47.1
>