[PATCH v7 0/4] misc: fastrpc: Add polling mode support

[PATCH v7 0/4] misc: fastrpc: Add polling mode support

[Ekansh Gupta]

This patch series adds polling mode feature that have been missing in
upstream FastRPC driver.

- Add changes to move fdlist to ctx structure to avoid code duplicacy.
- Update context mask to support polling mode.
- Add changes to support polling feature.

Userspace change: https://github.com/qualcomm/fastrpc/pull/258
Patch [v6]: https://lore.kernel.org/all/20260215182136.3995111-1-ekansh.gupta@oss.qualcomm.com/

Changes in v6:
  - Fixed warnings.
  - Fixed commit text.
  - Addressed clean-up comments.

Changes in v5:
  - Fixed poll memory calculation.
  - Added few formatting changes.

Changes in v5:
  - Add more details in commit text.

Changes in v4:
  - Replace hardcoded ctxid mask with GENMASK.
  - Fixed commit text.

Changes in v3:
  - Resolve compilation warning.

Changes in v2:
  - Added comments and fixed commit text.
  - Defined context id position as a macro.
  - Added new IOCTL to control polling mode as always enabling
    it might cause excess power consumption.
  - Cleaned up polling mode implementation.

Ekansh Gupta (4):
  misc: fastrpc: Move fdlist to invoke context structure
  misc: fastrpc: Replace hardcoded ctxid mask with GENMASK
  misc: fastrpc: Expand context ID mask for DSP polling mode support
  misc: fastrpc: Add polling mode support for fastRPC driver

 drivers/misc/fastrpc.c      | 154 +++++++++++++++++++++++++++++++-----
 include/uapi/misc/fastrpc.h |  10 +++
 2 files changed, 144 insertions(+), 20 deletions(-)

-- 
2.34.1

[PATCH v7 1/4] misc: fastrpc: Move fdlist to invoke context structure

[Ekansh Gupta]

The fdlist is currently part of the meta buffer which is set during
fastrpc_get_args(), this fdlist is getting recalculated during
fastrpc_put_args().

Move fdlist to the invoke context structure to improve maintainability
and reduce redundancy. This centralizes its handling and simplifies
meta buffer preparation and reading logic.

Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
---
 drivers/misc/fastrpc.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 47356a5d5804..11f4ae749e51 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -233,6 +233,7 @@ struct fastrpc_invoke_ctx {
 	int pid;
 	int client_id;
 	u32 sc;
+	u64 *fdlist;
 	u32 *crc;
 	u64 ctxid;
 	u64 msg_sz;
@@ -1016,6 +1017,7 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
 	rpra = ctx->buf->virt;
 	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
 	pages = fastrpc_phy_page_start(list, ctx->nscalars);
+	ctx->fdlist = (u64 *)(pages + ctx->nscalars);
 	args = (uintptr_t)ctx->buf->virt + metalen;
 	rlen = pkt_size - metalen;
 	ctx->rpra = rpra;
@@ -1118,18 +1120,11 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
 	union fastrpc_remote_arg *rpra = ctx->rpra;
 	struct fastrpc_user *fl = ctx->fl;
 	struct fastrpc_map *mmap = NULL;
-	struct fastrpc_invoke_buf *list;
-	struct fastrpc_phy_page *pages;
-	u64 *fdlist;
-	int i, inbufs, outbufs, handles;
+	u64 *fdlist = ctx->fdlist;
+	int i, inbufs;
 	int ret = 0;
 
 	inbufs = REMOTE_SCALARS_INBUFS(ctx->sc);
-	outbufs = REMOTE_SCALARS_OUTBUFS(ctx->sc);
-	handles = REMOTE_SCALARS_INHANDLES(ctx->sc) + REMOTE_SCALARS_OUTHANDLES(ctx->sc);
-	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
-	pages = fastrpc_phy_page_start(list, ctx->nscalars);
-	fdlist = (uint64_t *)(pages + inbufs + outbufs + handles);
 
 	for (i = inbufs; i < ctx->nbufs; ++i) {
 		if (!ctx->maps[i]) {
-- 
2.34.1

Re: [PATCH v7 1/4] misc: fastrpc: Move fdlist to invoke context structure

[Srinivas Kandagatla]

On 4/2/26 5:49 AM, Ekansh Gupta wrote:
> The fdlist is currently part of the meta buffer which is set during
> fastrpc_get_args(), this fdlist is getting recalculated during
> fastrpc_put_args().
> 
> Move fdlist to the invoke context structure to improve maintainability
> and reduce redundancy. This centralizes its handling and simplifies
> meta buffer preparation and reading logic.
> 
> Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
> ---
>  drivers/misc/fastrpc.c | 13 ++++---------
>  1 file changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 47356a5d5804..11f4ae749e51 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -233,6 +233,7 @@ struct fastrpc_invoke_ctx {
>  	int pid;
>  	int client_id;
>  	u32 sc;
> +	u64 *fdlist;
>  	u32 *crc;
>  	u64 ctxid;
>  	u64 msg_sz;
> @@ -1016,6 +1017,7 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
>  	rpra = ctx->buf->virt;
>  	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
>  	pages = fastrpc_phy_page_start(list, ctx->nscalars);
> +	ctx->fdlist = (u64 *)(pages + ctx->nscalars);
>  	args = (uintptr_t)ctx->buf->virt + metalen;
>  	rlen = pkt_size - metalen;
>  	ctx->rpra = rpra;
> @@ -1118,18 +1120,11 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
>  	union fastrpc_remote_arg *rpra = ctx->rpra;
>  	struct fastrpc_user *fl = ctx->fl;
>  	struct fastrpc_map *mmap = NULL;
> -	struct fastrpc_invoke_buf *list;
> -	struct fastrpc_phy_page *pages;
> -	u64 *fdlist;
> -	int i, inbufs, outbufs, handles;
> +	u64 *fdlist = ctx->fdlist;

fdlist is available after input , output buffers and handles.

why this is now changed to nscalars?

--srini
> +	int i, inbufs;
>  	int ret = 0;
>  
>  	inbufs = REMOTE_SCALARS_INBUFS(ctx->sc);
> -	outbufs = REMOTE_SCALARS_OUTBUFS(ctx->sc);
> -	handles = REMOTE_SCALARS_INHANDLES(ctx->sc) + REMOTE_SCALARS_OUTHANDLES(ctx->sc);
> -	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
> -	pages = fastrpc_phy_page_start(list, ctx->nscalars);
> -	fdlist = (uint64_t *)(pages + inbufs + outbufs + handles);
>  
>  	for (i = inbufs; i < ctx->nbufs; ++i) {
>  		if (!ctx->maps[i]) {

Re: [PATCH v7 1/4] misc: fastrpc: Move fdlist to invoke context structure

[Ekansh Gupta]

On 13-04-2026 19:38, Srinivas Kandagatla wrote:
> 
> 
> On 4/2/26 5:49 AM, Ekansh Gupta wrote:
>> The fdlist is currently part of the meta buffer which is set during
>> fastrpc_get_args(), this fdlist is getting recalculated during
>> fastrpc_put_args().
>>
>> Move fdlist to the invoke context structure to improve maintainability
>> and reduce redundancy. This centralizes its handling and simplifies
>> meta buffer preparation and reading logic.
>>
>> Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
>> ---
>>  drivers/misc/fastrpc.c | 13 ++++---------
>>  1 file changed, 4 insertions(+), 9 deletions(-)
>>
>> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
>> index 47356a5d5804..11f4ae749e51 100644
>> --- a/drivers/misc/fastrpc.c
>> +++ b/drivers/misc/fastrpc.c
>> @@ -233,6 +233,7 @@ struct fastrpc_invoke_ctx {
>>  	int pid;
>>  	int client_id;
>>  	u32 sc;
>> +	u64 *fdlist;
>>  	u32 *crc;
>>  	u64 ctxid;
>>  	u64 msg_sz;
>> @@ -1016,6 +1017,7 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
>>  	rpra = ctx->buf->virt;
>>  	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
>>  	pages = fastrpc_phy_page_start(list, ctx->nscalars);
>> +	ctx->fdlist = (u64 *)(pages + ctx->nscalars);
>>  	args = (uintptr_t)ctx->buf->virt + metalen;
>>  	rlen = pkt_size - metalen;
>>  	ctx->rpra = rpra;
>> @@ -1118,18 +1120,11 @@ static int fastrpc_put_args(struct fastrpc_invoke_ctx *ctx,
>>  	union fastrpc_remote_arg *rpra = ctx->rpra;
>>  	struct fastrpc_user *fl = ctx->fl;
>>  	struct fastrpc_map *mmap = NULL;
>> -	struct fastrpc_invoke_buf *list;
>> -	struct fastrpc_phy_page *pages;
>> -	u64 *fdlist;
>> -	int i, inbufs, outbufs, handles;
>> +	u64 *fdlist = ctx->fdlist;
> 
> fdlist is available after input , output buffers and handles.
> 
> why this is now changed to nscalars?
We can replace it as,

nscalars = inbufs + outbufs + handles


> 
> --srini
>> +	int i, inbufs;
>>  	int ret = 0;
>>  
>>  	inbufs = REMOTE_SCALARS_INBUFS(ctx->sc);
>> -	outbufs = REMOTE_SCALARS_OUTBUFS(ctx->sc);
>> -	handles = REMOTE_SCALARS_INHANDLES(ctx->sc) + REMOTE_SCALARS_OUTHANDLES(ctx->sc);
>> -	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
>> -	pages = fastrpc_phy_page_start(list, ctx->nscalars);
>> -	fdlist = (uint64_t *)(pages + inbufs + outbufs + handles);
>>  
>>  	for (i = inbufs; i < ctx->nbufs; ++i) {
>>  		if (!ctx->maps[i]) {
> 

[PATCH v7 2/4] misc: fastrpc: Replace hardcoded ctxid mask with GENMASK

[Ekansh Gupta]

Replace the hardcoded context ID mask (0xFF0) with GENMASK(11, 4) to
improve readability and follow kernel bitfield conventions. Use
FIELD_PREP and FIELD_GET instead of manual shifts for setting and
extracting ctxid values.

Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
---
 drivers/misc/fastrpc.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 11f4ae749e51..ce4874b9480e 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -23,6 +23,7 @@
 #include <uapi/misc/fastrpc.h>
 #include <linux/of_reserved_mem.h>
 #include <linux/bits.h>
+#include <linux/bitops.h>
 
 #define ADSP_DOMAIN_ID (0)
 #define MDSP_DOMAIN_ID (1)
@@ -37,7 +38,7 @@
 #define FASTRPC_CTX_MAX (256)
 #define FASTRPC_INIT_HANDLE	1
 #define FASTRPC_DSP_UTILITIES_HANDLE	2
-#define FASTRPC_CTXID_MASK (0xFF0)
+#define FASTRPC_CTXID_MASK GENMASK(11, 4)
 #define INIT_FILELEN_MAX (2 * 1024 * 1024)
 #define INIT_FILE_NAMELEN_MAX (128)
 #define FASTRPC_DEVICE_NAME	"fastrpc"
@@ -515,7 +516,7 @@ static void fastrpc_context_free(struct kref *ref)
 		fastrpc_buf_free(ctx->buf);
 
 	spin_lock_irqsave(&cctx->lock, flags);
-	idr_remove(&cctx->ctx_idr, ctx->ctxid >> 4);
+	idr_remove(&cctx->ctx_idr, FIELD_GET(FASTRPC_CTXID_MASK, ctx->ctxid));
 	spin_unlock_irqrestore(&cctx->lock, flags);
 
 	kfree(ctx->maps);
@@ -649,7 +650,7 @@ static struct fastrpc_invoke_ctx *fastrpc_context_alloc(
 		spin_unlock_irqrestore(&cctx->lock, flags);
 		goto err_idr;
 	}
-	ctx->ctxid = ret << 4;
+	ctx->ctxid = FIELD_PREP(FASTRPC_CTXID_MASK, ret);
 	spin_unlock_irqrestore(&cctx->lock, flags);
 
 	kref_init(&ctx->refcount);
@@ -2505,7 +2506,7 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
 	if (len < sizeof(*rsp))
 		return -EINVAL;
 
-	ctxid = ((rsp->ctx & FASTRPC_CTXID_MASK) >> 4);
+	ctxid = FIELD_GET(FASTRPC_CTXID_MASK, rsp->ctx);
 
 	spin_lock_irqsave(&cctx->lock, flags);
 	ctx = idr_find(&cctx->ctx_idr, ctxid);
-- 
2.34.1

[PATCH v7 3/4] misc: fastrpc: Expand context ID mask for DSP polling mode support

[Ekansh Gupta]

Current FastRPC context uses a 12-bit mask:
  [ID(8 bits)][PD type(4 bits)] = GENMASK(11, 4)

This works for normal calls but fails for DSP polling mode.
Polling mode expects a 16-bit layout:
  [15:8] = context ID (8 bits)
  [7:5]  = reserved
  [4]    = async mode bit
  [3:0]  = PD type (4 bits)

If async bit (bit 4) is set, DSP disables polling. With current
mask, odd IDs can set this bit, causing DSP to skip poll updates.

Update FASTRPC_CTXID_MASK to GENMASK(15, 8) so IDs occupy upper
byte and lower byte is left for DSP flags and PD type.

Reserved bits remain unused. This change is compatible with
polling mode and does not break non-polling behavior.

Bit layout:
  [15:8] = CCCCCCCC (context ID)
  [7:5]  = xxx (reserved)
  [4]    = A (async mode)
  [3:0]  = PPPP (PD type)

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
---
 drivers/misc/fastrpc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index ce4874b9480e..4363e0cc296b 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -38,7 +38,7 @@
 #define FASTRPC_CTX_MAX (256)
 #define FASTRPC_INIT_HANDLE	1
 #define FASTRPC_DSP_UTILITIES_HANDLE	2
-#define FASTRPC_CTXID_MASK GENMASK(11, 4)
+#define FASTRPC_CTXID_MASK GENMASK(15, 8)
 #define INIT_FILELEN_MAX (2 * 1024 * 1024)
 #define INIT_FILE_NAMELEN_MAX (128)
 #define FASTRPC_DEVICE_NAME	"fastrpc"
-- 
2.34.1

[PATCH v7 4/4] misc: fastrpc: Add polling mode support for fastRPC driver

[Ekansh Gupta]

For any remote call to DSP, after sending an invocation message,
fastRPC driver waits for glink response and during this time the
CPU can go into low power modes. This adds latency to overall fastrpc
call as CPU wakeup and scheduling latencies are included. Add polling
mode support with which fastRPC driver will poll continuously on a
memory after sending a message to remote subsystem which will eliminate
CPU wakeup and scheduling latencies and reduce fastRPC overhead. In case
poll timeout happens, the call will fallback to normal RPC mode.  Poll
mode can be enabled by user by using FASTRPC_IOCTL_SET_OPTION ioctl
request with FASTRPC_POLL_MODE request id.

Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
---
 drivers/misc/fastrpc.c      | 132 ++++++++++++++++++++++++++++++++++--
 include/uapi/misc/fastrpc.h |  10 +++
 2 files changed, 135 insertions(+), 7 deletions(-)

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 4363e0cc296b..25f385f4704d 100644
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -24,6 +24,8 @@
 #include <linux/of_reserved_mem.h>
 #include <linux/bits.h>
 #include <linux/bitops.h>
+#include <linux/compiler.h>
+#include <linux/iopoll.h>
 
 #define ADSP_DOMAIN_ID (0)
 #define MDSP_DOMAIN_ID (1)
@@ -38,6 +40,7 @@
 #define FASTRPC_CTX_MAX (256)
 #define FASTRPC_INIT_HANDLE	1
 #define FASTRPC_DSP_UTILITIES_HANDLE	2
+#define FASTRPC_MAX_STATIC_HANDLE (20)
 #define FASTRPC_CTXID_MASK GENMASK(15, 8)
 #define INIT_FILELEN_MAX (2 * 1024 * 1024)
 #define INIT_FILE_NAMELEN_MAX (128)
@@ -106,6 +109,12 @@
 
 #define miscdev_to_fdevice(d) container_of(d, struct fastrpc_device, miscdev)
 
+/* Poll response number from remote processor for call completion */
+#define FASTRPC_POLL_RESPONSE (0xdecaf)
+
+/* Polling mode timeout limit */
+#define FASTRPC_POLL_MAX_TIMEOUT_US (10000)
+
 struct fastrpc_phy_page {
 	dma_addr_t addr;	/* dma address */
 	u64 size;		/* size of contiguous region */
@@ -236,8 +245,14 @@ struct fastrpc_invoke_ctx {
 	u32 sc;
 	u64 *fdlist;
 	u32 *crc;
+	/* Poll memory that DSP updates */
+	u32 *poll;
 	u64 ctxid;
 	u64 msg_sz;
+	/* work done status flag */
+	bool is_work_done;
+	/* process updates poll memory instead of glink response */
+	bool is_polled;
 	struct kref refcount;
 	struct list_head node; /* list of ctxs */
 	struct completion work;
@@ -308,6 +323,8 @@ struct fastrpc_user {
 	int client_id;
 	int pd;
 	bool is_secure_dev;
+	/* Flags poll mode state */
+	bool poll_mode;
 	/* Lock for lists */
 	spinlock_t lock;
 	/* lock for allocations */
@@ -923,7 +940,8 @@ static int fastrpc_get_meta_size(struct fastrpc_invoke_ctx *ctx)
 		sizeof(struct fastrpc_invoke_buf) +
 		sizeof(struct fastrpc_phy_page)) * ctx->nscalars +
 		sizeof(u64) * FASTRPC_MAX_FDLIST +
-		sizeof(u32) * FASTRPC_MAX_CRCLIST;
+		sizeof(u32) * FASTRPC_MAX_CRCLIST +
+		sizeof(u32);
 
 	return size;
 }
@@ -1019,6 +1037,9 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
 	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
 	pages = fastrpc_phy_page_start(list, ctx->nscalars);
 	ctx->fdlist = (u64 *)(pages + ctx->nscalars);
+	ctx->poll = (u32 *)((uintptr_t)ctx->fdlist + sizeof(u64) * FASTRPC_MAX_FDLIST +
+			     sizeof(u32) * FASTRPC_MAX_CRCLIST);
+
 	args = (uintptr_t)ctx->buf->virt + metalen;
 	rlen = pkt_size - metalen;
 	ctx->rpra = rpra;
@@ -1188,6 +1209,74 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
 
 }
 
+static inline u32 fastrpc_poll_op(void *p)
+{
+	struct fastrpc_invoke_ctx *ctx = p;
+
+	dma_rmb();
+	return READ_ONCE(*ctx->poll);
+}
+
+static int poll_for_remote_response(struct fastrpc_invoke_ctx *ctx)
+{
+	u32 val;
+	int ret;
+
+	/*
+	 * Poll until DSP writes FASTRPC_POLL_RESPONSE into *ctx->poll
+	 * or until another path marks the work done.
+	 */
+	ret = read_poll_timeout_atomic(fastrpc_poll_op, val,
+				       (val == FASTRPC_POLL_RESPONSE) || ctx->is_work_done, 1,
+				       FASTRPC_POLL_MAX_TIMEOUT_US, false, ctx);
+
+	if (!ret && val == FASTRPC_POLL_RESPONSE) {
+		ctx->is_work_done = true;
+		ctx->retval = 0;
+	}
+
+	if (ret == -ETIMEDOUT)
+		ret = -EIO;
+
+	return ret;
+}
+
+static inline int fastrpc_wait_for_response(struct fastrpc_invoke_ctx *ctx,
+					    u32 kernel)
+{
+	int err = 0;
+
+	if (kernel) {
+		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
+			err = -ETIMEDOUT;
+	} else {
+		err = wait_for_completion_interruptible(&ctx->work);
+	}
+
+	return err;
+}
+
+static int fastrpc_wait_for_completion(struct fastrpc_invoke_ctx *ctx,
+				       u32 kernel)
+{
+	int err;
+
+	do {
+		if (ctx->is_polled) {
+			err = poll_for_remote_response(ctx);
+			/* If polling timed out, move to normal response mode */
+			if (err)
+				ctx->is_polled = false;
+		} else {
+			err = fastrpc_wait_for_response(ctx, kernel);
+			if (err)
+				return err;
+		}
+	} while (!ctx->is_work_done);
+
+	return 0;
+}
+
 static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
 				   u32 handle, u32 sc,
 				   struct fastrpc_invoke_args *args)
@@ -1223,13 +1312,14 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
 	if (err)
 		goto bail;
 
-	if (kernel) {
-		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
-			err = -ETIMEDOUT;
-	} else {
-		err = wait_for_completion_interruptible(&ctx->work);
-	}
+	/*
+	 * Set message context as polled if the call is for a user PD
+	 * dynamic module and user has enabled poll mode.
+	 */
+	if (handle > FASTRPC_MAX_STATIC_HANDLE && fl->pd == USER_PD && fl->poll_mode)
+		ctx->is_polled = true;
 
+	err = fastrpc_wait_for_completion(ctx, kernel);
 	if (err)
 		goto bail;
 
@@ -1812,6 +1902,30 @@ static int fastrpc_get_info_from_kernel(struct fastrpc_ioctl_capability *cap,
 	return 0;
 }
 
+static int fastrpc_set_option(struct fastrpc_user *fl, char __user *argp)
+{
+	struct fastrpc_ioctl_set_option opt = {0};
+	int i;
+
+	if (copy_from_user(&opt, argp, sizeof(opt)))
+		return -EFAULT;
+
+	for (i = 0; i < ARRAY_SIZE(opt.reserved); i++) {
+		if (opt.reserved[i] != 0)
+			return -EINVAL;
+	}
+
+	if (opt.req != FASTRPC_POLL_MODE)
+		return -EINVAL;
+
+	if (opt.value)
+		fl->poll_mode = true;
+	else
+		fl->poll_mode = false;
+
+	return 0;
+}
+
 static int fastrpc_get_dsp_info(struct fastrpc_user *fl, char __user *argp)
 {
 	struct fastrpc_ioctl_capability cap = {0};
@@ -2167,6 +2281,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
 	case FASTRPC_IOCTL_MEM_UNMAP:
 		err = fastrpc_req_mem_unmap(fl, argp);
 		break;
+	case FASTRPC_IOCTL_SET_OPTION:
+		err = fastrpc_set_option(fl, argp);
+		break;
 	case FASTRPC_IOCTL_GET_DSP_INFO:
 		err = fastrpc_get_dsp_info(fl, argp);
 		break;
@@ -2518,6 +2635,7 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
 	}
 
 	ctx->retval = rsp->retval;
+	ctx->is_work_done = true;
 	complete(&ctx->work);
 
 	/*
diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h
index c6e2925f47e6..c37e24a764ae 100644
--- a/include/uapi/misc/fastrpc.h
+++ b/include/uapi/misc/fastrpc.h
@@ -16,6 +16,7 @@
 #define FASTRPC_IOCTL_INIT_CREATE_STATIC _IOWR('R', 9, struct fastrpc_init_create_static)
 #define FASTRPC_IOCTL_MEM_MAP		_IOWR('R', 10, struct fastrpc_mem_map)
 #define FASTRPC_IOCTL_MEM_UNMAP		_IOWR('R', 11, struct fastrpc_mem_unmap)
+#define FASTRPC_IOCTL_SET_OPTION	_IOWR('R', 12, struct fastrpc_ioctl_set_option)
 #define FASTRPC_IOCTL_GET_DSP_INFO	_IOWR('R', 13, struct fastrpc_ioctl_capability)
 
 /**
@@ -67,6 +68,9 @@ enum fastrpc_proc_attr {
 /* Fastrpc attribute for memory protection of buffers */
 #define FASTRPC_ATTR_SECUREMAP	(1)
 
+/* Set option request ID to enable poll mode */
+#define FASTRPC_POLL_MODE	(1)
+
 struct fastrpc_invoke_args {
 	__u64 ptr;
 	__u64 length;
@@ -133,6 +137,12 @@ struct fastrpc_mem_unmap {
 	__s32 reserved[5];
 };
 
+struct fastrpc_ioctl_set_option {
+	__u32 req;	/* request id */
+	__u32 value;	/* value */
+	__s32 reserved[6];
+};
+
 struct fastrpc_ioctl_capability {
 	__u32 unused; /* deprecated, ignored by the kernel */
 	__u32 attribute_id;
-- 
2.34.1

Re: [PATCH v7 4/4] misc: fastrpc: Add polling mode support for fastRPC driver

[Srinivas Kandagatla]

On 4/2/26 5:49 AM, Ekansh Gupta wrote:
> For any remote call to DSP, after sending an invocation message,
> fastRPC driver waits for glink response and during this time the
> CPU can go into low power modes. This adds latency to overall fastrpc
> call as CPU wakeup and scheduling latencies are included. Add polling
> mode support with which fastRPC driver will poll continuously on a
> memory after sending a message to remote subsystem which will eliminate
> CPU wakeup and scheduling latencies and reduce fastRPC overhead. In case
> poll timeout happens, the call will fallback to normal RPC mode.  Poll
> mode can be enabled by user by using FASTRPC_IOCTL_SET_OPTION ioctl
> request with FASTRPC_POLL_MODE request id.
> 
> Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
> ---
>  drivers/misc/fastrpc.c      | 132 ++++++++++++++++++++++++++++++++++--
>  include/uapi/misc/fastrpc.h |  10 +++
>  2 files changed, 135 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
> index 4363e0cc296b..25f385f4704d 100644
> --- a/drivers/misc/fastrpc.c
> +++ b/drivers/misc/fastrpc.c
> @@ -24,6 +24,8 @@
>  #include <linux/of_reserved_mem.h>
>  #include <linux/bits.h>
>  #include <linux/bitops.h>
> +#include <linux/compiler.h>
> +#include <linux/iopoll.h>
>  
>  #define ADSP_DOMAIN_ID (0)
>  #define MDSP_DOMAIN_ID (1)
> @@ -38,6 +40,7 @@
>  #define FASTRPC_CTX_MAX (256)
>  #define FASTRPC_INIT_HANDLE	1
>  #define FASTRPC_DSP_UTILITIES_HANDLE	2
> +#define FASTRPC_MAX_STATIC_HANDLE (20)
Document please.

>  #define FASTRPC_CTXID_MASK GENMASK(15, 8)
>  #define INIT_FILELEN_MAX (2 * 1024 * 1024)
>  #define INIT_FILE_NAMELEN_MAX (128)
> @@ -106,6 +109,12 @@
>  
>  #define miscdev_to_fdevice(d) container_of(d, struct fastrpc_device, miscdev)
>  
> +/* Poll response number from remote processor for call completion */
> +#define FASTRPC_POLL_RESPONSE (0xdecaf)
> +
> +/* Polling mode timeout limit */
> +#define FASTRPC_POLL_MAX_TIMEOUT_US (10000)
> +
>  struct fastrpc_phy_page {
>  	dma_addr_t addr;	/* dma address */
>  	u64 size;		/* size of contiguous region */
> @@ -236,8 +245,14 @@ struct fastrpc_invoke_ctx {
>  	u32 sc;
>  	u64 *fdlist;
>  	u32 *crc;
> +	/* Poll memory that DSP updates */
> +	u32 *poll;
>  	u64 ctxid;
>  	u64 msg_sz;
> +	/* work done status flag */
> +	bool is_work_done;
> +	/* process updates poll memory instead of glink response */
> +	bool is_polled;
This looks redundant as the user context already has this info.

>  	struct kref refcount;
>  	struct list_head node; /* list of ctxs */
>  	struct completion work;
> @@ -308,6 +323,8 @@ struct fastrpc_user {
>  	int client_id;
>  	int pd;
>  	bool is_secure_dev;
> +	/* Flags poll mode state */
> +	bool poll_mode;
>  	/* Lock for lists */
>  	spinlock_t lock;
>  	/* lock for allocations */
> @@ -923,7 +940,8 @@ static int fastrpc_get_meta_size(struct fastrpc_invoke_ctx *ctx)
>  		sizeof(struct fastrpc_invoke_buf) +
>  		sizeof(struct fastrpc_phy_page)) * ctx->nscalars +
>  		sizeof(u64) * FASTRPC_MAX_FDLIST +
> -		sizeof(u32) * FASTRPC_MAX_CRCLIST;
> +		sizeof(u32) * FASTRPC_MAX_CRCLIST +
> +		sizeof(u32);
>  
>  	return size;
>  }
> @@ -1019,6 +1037,9 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
>  	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
>  	pages = fastrpc_phy_page_start(list, ctx->nscalars);
>  	ctx->fdlist = (u64 *)(pages + ctx->nscalars);
> +	ctx->poll = (u32 *)((uintptr_t)ctx->fdlist + sizeof(u64) * FASTRPC_MAX_FDLIST +
> +			     sizeof(u32) * FASTRPC_MAX_CRCLIST);
> +
>  	args = (uintptr_t)ctx->buf->virt + metalen;
>  	rlen = pkt_size - metalen;
>  	ctx->rpra = rpra;
> @@ -1188,6 +1209,74 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
>  
>  }
>  
> +static inline u32 fastrpc_poll_op(void *p)
> +{
> +	struct fastrpc_invoke_ctx *ctx = p;
> +
> +	dma_rmb();
> +	return READ_ONCE(*ctx->poll);
> +}
> +
> +static int poll_for_remote_response(struct fastrpc_invoke_ctx *ctx)
> +{
> +	u32 val;
> +	int ret;
> +
> +	/*
> +	 * Poll until DSP writes FASTRPC_POLL_RESPONSE into *ctx->poll
> +	 * or until another path marks the work done.
> +	 */
> +	ret = read_poll_timeout_atomic(fastrpc_poll_op, val,
> +				       (val == FASTRPC_POLL_RESPONSE) || ctx->is_work_done, 1,
> +				       FASTRPC_POLL_MAX_TIMEOUT_US, false, ctx);

What happens if the dsp sends normal response with rpcmsg callback while
the loop is still going on?

> +
> +	if (!ret && val == FASTRPC_POLL_RESPONSE) {
check redundant?

> +		ctx->is_work_done = true;
> +		ctx->retval = 0;
> +	}
> +
> +	if (ret == -ETIMEDOUT)
> +		ret = -EIO;
> +
> +	return ret;
> +}
> +
> +static inline int fastrpc_wait_for_response(struct fastrpc_invoke_ctx *ctx,
> +					    u32 kernel)
> +{
> +	int err = 0;
> +
> +	if (kernel) {
> +		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
> +			err = -ETIMEDOUT;
> +	} else {
> +		err = wait_for_completion_interruptible(&ctx->work);
> +	}
> +
> +	return err;
> +}
> +
> +static int fastrpc_wait_for_completion(struct fastrpc_invoke_ctx *ctx,
> +				       u32 kernel)
> +{
> +	int err;
> +
> +	do {
> +		if (ctx->is_polled) {
> +			err = poll_for_remote_response(ctx);
> +			/* If polling timed out, move to normal response mode */
> +			if (err)
> +				ctx->is_polled = false;
> +		} else {
> +			err = fastrpc_wait_for_response(ctx, kernel);
> +			if (err)
> +				return err;
> +		}
> +	} while (!ctx->is_work_done);
> +
> +	return 0;
> +}
> +
>  static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
>  				   u32 handle, u32 sc,
>  				   struct fastrpc_invoke_args *args)
> @@ -1223,13 +1312,14 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
>  	if (err)
>  		goto bail;
>  
> -	if (kernel) {
> -		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
> -			err = -ETIMEDOUT;
> -	} else {
> -		err = wait_for_completion_interruptible(&ctx->work);
> -	}
> +	/*
> +	 * Set message context as polled if the call is for a user PD
> +	 * dynamic module and user has enabled poll mode.
> +	 */
> +	if (handle > FASTRPC_MAX_STATIC_HANDLE && fl->pd == USER_PD && fl->poll_mode)
> +		ctx->is_polled = true;

There seems to be some level of validation here, which is not clearly
documented anywhere, can we add this into uapi header please.

>  
> +	err = fastrpc_wait_for_completion(ctx, kernel);
>  	if (err)
>  		goto bail;
>  
> @@ -1812,6 +1902,30 @@ static int fastrpc_get_info_from_kernel(struct fastrpc_ioctl_capability *cap,
>  	return 0;
>  }
>  
> +static int fastrpc_set_option(struct fastrpc_user *fl, char __user *argp)
> +{
> +	struct fastrpc_ioctl_set_option opt = {0};
> +	int i;
> +
> +	if (copy_from_user(&opt, argp, sizeof(opt)))
> +		return -EFAULT;
> +
> +	for (i = 0; i < ARRAY_SIZE(opt.reserved); i++) {
> +		if (opt.reserved[i] != 0)
> +			return -EINVAL;
> +	}
> +
> +	if (opt.req != FASTRPC_POLL_MODE)
> +		return -EINVAL;
> +
> +	if (opt.value)
> +		fl->poll_mode = true;
> +	else
> +		fl->poll_mode = false;
> +
> +	return 0;
> +}
> +
>  static int fastrpc_get_dsp_info(struct fastrpc_user *fl, char __user *argp)
>  {
>  	struct fastrpc_ioctl_capability cap = {0};
> @@ -2167,6 +2281,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
>  	case FASTRPC_IOCTL_MEM_UNMAP:
>  		err = fastrpc_req_mem_unmap(fl, argp);
>  		break;
> +	case FASTRPC_IOCTL_SET_OPTION:
> +		err = fastrpc_set_option(fl, argp);
> +		break;
>  	case FASTRPC_IOCTL_GET_DSP_INFO:
>  		err = fastrpc_get_dsp_info(fl, argp);
>  		break;
> @@ -2518,6 +2635,7 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
>  	}
>  
>  	ctx->retval = rsp->retval;
> +	ctx->is_work_done = true;
>  	complete(&ctx->work);
>  
>  	/*
> diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h
> index c6e2925f47e6..c37e24a764ae 100644
> --- a/include/uapi/misc/fastrpc.h
> +++ b/include/uapi/misc/fastrpc.h
> @@ -16,6 +16,7 @@
>  #define FASTRPC_IOCTL_INIT_CREATE_STATIC _IOWR('R', 9, struct fastrpc_init_create_static)
>  #define FASTRPC_IOCTL_MEM_MAP		_IOWR('R', 10, struct fastrpc_mem_map)
>  #define FASTRPC_IOCTL_MEM_UNMAP		_IOWR('R', 11, struct fastrpc_mem_unmap)
> +#define FASTRPC_IOCTL_SET_OPTION	_IOWR('R', 12, struct fastrpc_ioctl_set_option)
>  #define FASTRPC_IOCTL_GET_DSP_INFO	_IOWR('R', 13, struct fastrpc_ioctl_capability)
>  
>  /**
> @@ -67,6 +68,9 @@ enum fastrpc_proc_attr {
>  /* Fastrpc attribute for memory protection of buffers */
>  #define FASTRPC_ATTR_SECUREMAP	(1)
>  

> +/* Set option request ID to enable poll mode */

Some documentation please on this feature and which PD's can use this.

> +#define FASTRPC_POLL_MODE	(1)

Can we also document the values for this request?
> +
>  struct fastrpc_invoke_args {
>  	__u64 ptr;
>  	__u64 length;
> @@ -133,6 +137,12 @@ struct fastrpc_mem_unmap {
>  	__s32 reserved[5];
>  };
>  
> +struct fastrpc_ioctl_set_option {
> +	__u32 req;	/* request id */
Can we expand this to proper name, request_id or something?
> +	__u32 value;	/* value */
> +	__s32 reserved[6];
> +};
> +
>  struct fastrpc_ioctl_capability {
>  	__u32 unused; /* deprecated, ignored by the kernel */
>  	__u32 attribute_id;

Re: [PATCH v7 4/4] misc: fastrpc: Add polling mode support for fastRPC driver

[Ekansh Gupta]

On 13-04-2026 20:20, Srinivas Kandagatla wrote:
> 
> 
> On 4/2/26 5:49 AM, Ekansh Gupta wrote:
>> For any remote call to DSP, after sending an invocation message,
>> fastRPC driver waits for glink response and during this time the
>> CPU can go into low power modes. This adds latency to overall fastrpc
>> call as CPU wakeup and scheduling latencies are included. Add polling
>> mode support with which fastRPC driver will poll continuously on a
>> memory after sending a message to remote subsystem which will eliminate
>> CPU wakeup and scheduling latencies and reduce fastRPC overhead. In case
>> poll timeout happens, the call will fallback to normal RPC mode.  Poll
>> mode can be enabled by user by using FASTRPC_IOCTL_SET_OPTION ioctl
>> request with FASTRPC_POLL_MODE request id.
>>
>> Signed-off-by: Ekansh Gupta <ekansh.gupta@oss.qualcomm.com>
>> ---
>>  drivers/misc/fastrpc.c      | 132 ++++++++++++++++++++++++++++++++++--
>>  include/uapi/misc/fastrpc.h |  10 +++
>>  2 files changed, 135 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
>> index 4363e0cc296b..25f385f4704d 100644
>> --- a/drivers/misc/fastrpc.c
>> +++ b/drivers/misc/fastrpc.c
>> @@ -24,6 +24,8 @@
>>  #include <linux/of_reserved_mem.h>
>>  #include <linux/bits.h>
>>  #include <linux/bitops.h>
>> +#include <linux/compiler.h>
>> +#include <linux/iopoll.h>
>>  
>>  #define ADSP_DOMAIN_ID (0)
>>  #define MDSP_DOMAIN_ID (1)
>> @@ -38,6 +40,7 @@
>>  #define FASTRPC_CTX_MAX (256)
>>  #define FASTRPC_INIT_HANDLE	1
>>  #define FASTRPC_DSP_UTILITIES_HANDLE	2
>> +#define FASTRPC_MAX_STATIC_HANDLE (20)
> Document please.
ack
> 
>>  #define FASTRPC_CTXID_MASK GENMASK(15, 8)
>>  #define INIT_FILELEN_MAX (2 * 1024 * 1024)
>>  #define INIT_FILE_NAMELEN_MAX (128)
>> @@ -106,6 +109,12 @@
>>  
>>  #define miscdev_to_fdevice(d) container_of(d, struct fastrpc_device, miscdev)
>>  
>> +/* Poll response number from remote processor for call completion */
>> +#define FASTRPC_POLL_RESPONSE (0xdecaf)
>> +
>> +/* Polling mode timeout limit */
>> +#define FASTRPC_POLL_MAX_TIMEOUT_US (10000)
>> +
>>  struct fastrpc_phy_page {
>>  	dma_addr_t addr;	/* dma address */
>>  	u64 size;		/* size of contiguous region */
>> @@ -236,8 +245,14 @@ struct fastrpc_invoke_ctx {
>>  	u32 sc;
>>  	u64 *fdlist;
>>  	u32 *crc;
>> +	/* Poll memory that DSP updates */
>> +	u32 *poll;
>>  	u64 ctxid;
>>  	u64 msg_sz;
>> +	/* work done status flag */
>> +	bool is_work_done;
>> +	/* process updates poll memory instead of glink response */
>> +	bool is_polled;
> This looks redundant as the user context already has this info.
this is context specific flag. Not all context for a particular process
will go in polling path, so need to identify the same after sending
message to DSP.
> 
>>  	struct kref refcount;
>>  	struct list_head node; /* list of ctxs */
>>  	struct completion work;
>> @@ -308,6 +323,8 @@ struct fastrpc_user {
>>  	int client_id;
>>  	int pd;
>>  	bool is_secure_dev;
>> +	/* Flags poll mode state */
>> +	bool poll_mode;
>>  	/* Lock for lists */
>>  	spinlock_t lock;
>>  	/* lock for allocations */
>> @@ -923,7 +940,8 @@ static int fastrpc_get_meta_size(struct fastrpc_invoke_ctx *ctx)
>>  		sizeof(struct fastrpc_invoke_buf) +
>>  		sizeof(struct fastrpc_phy_page)) * ctx->nscalars +
>>  		sizeof(u64) * FASTRPC_MAX_FDLIST +
>> -		sizeof(u32) * FASTRPC_MAX_CRCLIST;
>> +		sizeof(u32) * FASTRPC_MAX_CRCLIST +
>> +		sizeof(u32);
>>  
>>  	return size;
>>  }
>> @@ -1019,6 +1037,9 @@ static int fastrpc_get_args(u32 kernel, struct fastrpc_invoke_ctx *ctx)
>>  	list = fastrpc_invoke_buf_start(rpra, ctx->nscalars);
>>  	pages = fastrpc_phy_page_start(list, ctx->nscalars);
>>  	ctx->fdlist = (u64 *)(pages + ctx->nscalars);
>> +	ctx->poll = (u32 *)((uintptr_t)ctx->fdlist + sizeof(u64) * FASTRPC_MAX_FDLIST +
>> +			     sizeof(u32) * FASTRPC_MAX_CRCLIST);
>> +
>>  	args = (uintptr_t)ctx->buf->virt + metalen;
>>  	rlen = pkt_size - metalen;
>>  	ctx->rpra = rpra;
>> @@ -1188,6 +1209,74 @@ static int fastrpc_invoke_send(struct fastrpc_session_ctx *sctx,
>>  
>>  }
>>  
>> +static inline u32 fastrpc_poll_op(void *p)
>> +{
>> +	struct fastrpc_invoke_ctx *ctx = p;
>> +
>> +	dma_rmb();
>> +	return READ_ONCE(*ctx->poll);
>> +}
>> +
>> +static int poll_for_remote_response(struct fastrpc_invoke_ctx *ctx)
>> +{
>> +	u32 val;
>> +	int ret;
>> +
>> +	/*
>> +	 * Poll until DSP writes FASTRPC_POLL_RESPONSE into *ctx->poll
>> +	 * or until another path marks the work done.
>> +	 */
>> +	ret = read_poll_timeout_atomic(fastrpc_poll_op, val,
>> +				       (val == FASTRPC_POLL_RESPONSE) || ctx->is_work_done, 1,
>> +				       FASTRPC_POLL_MAX_TIMEOUT_US, false, ctx);
> 
> What happens if the dsp sends normal response with rpcmsg callback while
> the loop is still going on?
the condition check also carries ctx->work_done which will get set in
case DSP sends normal response, hence the polling will stop in that case.
> 
>> +
>> +	if (!ret && val == FASTRPC_POLL_RESPONSE) {
> check redundant?
could be needed in normal response case, or in case polling fails.
> 
>> +		ctx->is_work_done = true;
>> +		ctx->retval = 0;
>> +	}
>> +
>> +	if (ret == -ETIMEDOUT)
>> +		ret = -EIO;
>> +
>> +	return ret;
>> +}
>> +
>> +static inline int fastrpc_wait_for_response(struct fastrpc_invoke_ctx *ctx,
>> +					    u32 kernel)
>> +{
>> +	int err = 0;
>> +
>> +	if (kernel) {
>> +		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
>> +			err = -ETIMEDOUT;
>> +	} else {
>> +		err = wait_for_completion_interruptible(&ctx->work);
>> +	}
>> +
>> +	return err;
>> +}
>> +
>> +static int fastrpc_wait_for_completion(struct fastrpc_invoke_ctx *ctx,
>> +				       u32 kernel)
>> +{
>> +	int err;
>> +
>> +	do {
>> +		if (ctx->is_polled) {
>> +			err = poll_for_remote_response(ctx);
>> +			/* If polling timed out, move to normal response mode */
>> +			if (err)
>> +				ctx->is_polled = false;
>> +		} else {
>> +			err = fastrpc_wait_for_response(ctx, kernel);
>> +			if (err)
>> +				return err;
>> +		}
>> +	} while (!ctx->is_work_done);
>> +
>> +	return 0;
>> +}
>> +
>>  static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
>>  				   u32 handle, u32 sc,
>>  				   struct fastrpc_invoke_args *args)
>> @@ -1223,13 +1312,14 @@ static int fastrpc_internal_invoke(struct fastrpc_user *fl,  u32 kernel,
>>  	if (err)
>>  		goto bail;
>>  
>> -	if (kernel) {
>> -		if (!wait_for_completion_timeout(&ctx->work, 10 * HZ))
>> -			err = -ETIMEDOUT;
>> -	} else {
>> -		err = wait_for_completion_interruptible(&ctx->work);
>> -	}
>> +	/*
>> +	 * Set message context as polled if the call is for a user PD
>> +	 * dynamic module and user has enabled poll mode.
>> +	 */
>> +	if (handle > FASTRPC_MAX_STATIC_HANDLE && fl->pd == USER_PD && fl->poll_mode)
>> +		ctx->is_polled = true;
> 
> There seems to be some level of validation here, which is not clearly
> documented anywhere, can we add this into uapi header please.
Ack. I'll add this detail when defining FASTRPC_POLL_MODE in uapi.
> 
>>  
>> +	err = fastrpc_wait_for_completion(ctx, kernel);
>>  	if (err)
>>  		goto bail;
>>  
>> @@ -1812,6 +1902,30 @@ static int fastrpc_get_info_from_kernel(struct fastrpc_ioctl_capability *cap,
>>  	return 0;
>>  }
>>  
>> +static int fastrpc_set_option(struct fastrpc_user *fl, char __user *argp)
>> +{
>> +	struct fastrpc_ioctl_set_option opt = {0};
>> +	int i;
>> +
>> +	if (copy_from_user(&opt, argp, sizeof(opt)))
>> +		return -EFAULT;
>> +
>> +	for (i = 0; i < ARRAY_SIZE(opt.reserved); i++) {
>> +		if (opt.reserved[i] != 0)
>> +			return -EINVAL;
>> +	}
>> +
>> +	if (opt.req != FASTRPC_POLL_MODE)
>> +		return -EINVAL;
>> +
>> +	if (opt.value)
>> +		fl->poll_mode = true;
>> +	else
>> +		fl->poll_mode = false;
>> +
>> +	return 0;
>> +}
>> +
>>  static int fastrpc_get_dsp_info(struct fastrpc_user *fl, char __user *argp)
>>  {
>>  	struct fastrpc_ioctl_capability cap = {0};
>> @@ -2167,6 +2281,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
>>  	case FASTRPC_IOCTL_MEM_UNMAP:
>>  		err = fastrpc_req_mem_unmap(fl, argp);
>>  		break;
>> +	case FASTRPC_IOCTL_SET_OPTION:
>> +		err = fastrpc_set_option(fl, argp);
>> +		break;
>>  	case FASTRPC_IOCTL_GET_DSP_INFO:
>>  		err = fastrpc_get_dsp_info(fl, argp);
>>  		break;
>> @@ -2518,6 +2635,7 @@ static int fastrpc_rpmsg_callback(struct rpmsg_device *rpdev, void *data,
>>  	}
>>  
>>  	ctx->retval = rsp->retval;
>> +	ctx->is_work_done = true;
>>  	complete(&ctx->work);
>>  
>>  	/*
>> diff --git a/include/uapi/misc/fastrpc.h b/include/uapi/misc/fastrpc.h
>> index c6e2925f47e6..c37e24a764ae 100644
>> --- a/include/uapi/misc/fastrpc.h
>> +++ b/include/uapi/misc/fastrpc.h
>> @@ -16,6 +16,7 @@
>>  #define FASTRPC_IOCTL_INIT_CREATE_STATIC _IOWR('R', 9, struct fastrpc_init_create_static)
>>  #define FASTRPC_IOCTL_MEM_MAP		_IOWR('R', 10, struct fastrpc_mem_map)
>>  #define FASTRPC_IOCTL_MEM_UNMAP		_IOWR('R', 11, struct fastrpc_mem_unmap)
>> +#define FASTRPC_IOCTL_SET_OPTION	_IOWR('R', 12, struct fastrpc_ioctl_set_option)
>>  #define FASTRPC_IOCTL_GET_DSP_INFO	_IOWR('R', 13, struct fastrpc_ioctl_capability)
>>  
>>  /**
>> @@ -67,6 +68,9 @@ enum fastrpc_proc_attr {
>>  /* Fastrpc attribute for memory protection of buffers */
>>  #define FASTRPC_ATTR_SECUREMAP	(1)
>>  
> 
>> +/* Set option request ID to enable poll mode */
> 
> Some documentation please on this feature and which PD's can use this.
ack
> 
>> +#define FASTRPC_POLL_MODE	(1)
> 
> Can we also document the values for this request?
ack
>> +
>>  struct fastrpc_invoke_args {
>>  	__u64 ptr;
>>  	__u64 length;
>> @@ -133,6 +137,12 @@ struct fastrpc_mem_unmap {
>>  	__s32 reserved[5];
>>  };
>>  
>> +struct fastrpc_ioctl_set_option {
>> +	__u32 req;	/* request id */
> Can we expand this to proper name, request_id or something?
I'll change it to request_id.

Thanks,
Ekansh
>> +	__u32 value;	/* value */
>> +	__s32 reserved[6];
>> +};
>> +
>>  struct fastrpc_ioctl_capability {
>>  	__u32 unused; /* deprecated, ignored by the kernel */
>>  	__u32 attribute_id;
>