[PATCH v2 2/2] soc: qcom: cmd-db: Stop memcpy()ing in cmd_db_read_aux_data()

[Stephen Boyd]

Let's change the function signature to return the pointer to memory or
an error pointer on failure, and take an argument that lets us return
the size of the aux data read. This way we can remove the
cmd_db_read_aux_data_len() API entirely and also get rid of the memcpy
operation from cmd_db to the caller.

Cc: Mahesh Sivasubramanian <msivasub@xxxxxxxxxxxxxx>
Cc: Lina Iyer <ilina@xxxxxxxxxxxxxx>
Cc: Bjorn Andersson <bjorn.andersson@xxxxxxxxxx>
Cc: Evan Green <evgreen@xxxxxxxxxxxx>
Cc: Jordan Crouse <jcrouse@xxxxxxxxxxxxxx>
Cc: Rob Clark <robdclark@xxxxxxxxx>
Signed-off-by: Stephen Boyd <swboyd@xxxxxxxxxxxx>
---
 drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 34 ++++++++++-----------
 drivers/soc/qcom/cmd-db.c             | 43 +++++----------------------
 include/soc/qcom/cmd-db.h             | 12 ++------
 3 files changed, 28 insertions(+), 61 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
index bbb8126ec5c5..e4387a3fa745 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
@@ -860,23 +860,23 @@ static int a6xx_gmu_memory_probe(struct a6xx_gmu *gmu)
 }
 
 /* Get the list of RPMh voltage levels from cmd-db */
-static int a6xx_gmu_rpmh_arc_cmds(const char *id, void *vals, int size)
+static const u16 *a6xx_gmu_rpmh_arc_cmds(const char *id, int *size)
 {
-	u32 len = cmd_db_read_aux_data_len(id);
-
-	if (!len)
-		return 0;
-
-	if (WARN_ON(len > size))
-		return -EINVAL;
-
-	cmd_db_read_aux_data(id, vals, len);
+	size_t len;
+	const u16 *vals;
 
+	vals = cmd_db_read_aux_data(id, &len);
 	/*
 	 * The data comes back as an array of unsigned shorts so adjust the
 	 * count accordingly
 	 */
-	return len >> 1;
+	len >>= 1;
+
+	if (!len || WARN_ON(len > 16))
+		len = 0;
+
+	*size = len;
+	return vals;
 }
 
 /* Return the 'arc-level' for the given frequency */
@@ -907,8 +907,8 @@ static u32 a6xx_gmu_get_arc_level(struct device *dev, unsigned long freq)
 
 static int a6xx_gmu_rpmh_arc_votes_init(struct device *dev, u32 *votes,
 		unsigned long *freqs, int freqs_count,
-		u16 *pri, int pri_count,
-		u16 *sec, int sec_count)
+		const u16 *pri, int pri_count,
+		const u16 *sec, int sec_count)
 {
 	int i, j;
 
@@ -970,14 +970,14 @@ static int a6xx_gmu_rpmh_votes_init(struct a6xx_gmu *gmu)
 	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
 	struct msm_gpu *gpu = &adreno_gpu->base;
 
-	u16 gx[16], cx[16], mx[16];
+	const u16 *gx, *cx, *mx;
 	u32 gxcount, cxcount, mxcount;
 	int ret;
 
 	/* Get the list of available voltage levels for each component */
-	gxcount = a6xx_gmu_rpmh_arc_cmds("gfx.lvl", gx, sizeof(gx));
-	cxcount = a6xx_gmu_rpmh_arc_cmds("cx.lvl", cx, sizeof(cx));
-	mxcount = a6xx_gmu_rpmh_arc_cmds("mx.lvl", mx, sizeof(mx));
+	gx = a6xx_gmu_rpmh_arc_cmds("gfx.lvl", &gxcount);
+	cx = a6xx_gmu_rpmh_arc_cmds("cx.lvl", &cxcount);
+	mx = a6xx_gmu_rpmh_arc_cmds("mx.lvl", &mxcount);
 
 	/* Build the GX votes */
 	ret = a6xx_gmu_rpmh_arc_votes_init(&gpu->pdev->dev, gmu->gx_arc_votes,
diff --git a/drivers/soc/qcom/cmd-db.c b/drivers/soc/qcom/cmd-db.c
index 5c9cc6824891..c701b3b010f1 100644
--- a/drivers/soc/qcom/cmd-db.c
+++ b/drivers/soc/qcom/cmd-db.c
@@ -192,55 +192,28 @@ EXPORT_SYMBOL(cmd_db_read_addr);
 /**
  * cmd_db_read_aux_data() - Query command db for aux data.
  *
- *  @id: Resource to retrieve AUX Data on.
- *  @data: Data buffer to copy returned aux data to. Returns size on NULL
- *  @len: Caller provides size of data buffer passed in.
+ *  @id: Resource to retrieve AUX Data on
+ *  @len: size of data buffer returned
  *
- *  Return: size of data on success, errno otherwise
+ *  Return: pointer to data on success, error pointer otherwise
  */
-int cmd_db_read_aux_data(const char *id, u8 *data, size_t len)
+const void *cmd_db_read_aux_data(const char *id, size_t *len)
 {
 	int ret;
 	const struct entry_header *ent;
 	const struct rsc_hdr *rsc_hdr;
-	u16 ent_len;
-
-	if (!data)
-		return -EINVAL;
 
 	ret = cmd_db_get_header(id, &ent, &rsc_hdr);
 	if (ret)
-		return ret;
-
-	ent_len = le16_to_cpu(ent->len);
-	if (len < ent_len)
-		return -EINVAL;
+		return ERR_PTR(ret);
 
-	len = min_t(u16, ent_len, len);
-	memcpy(data, rsc_offset(rsc_hdr, ent), len);
+	if (len)
+		*len = le16_to_cpu(ent->len);
 
-	return len;
+	return rsc_offset(rsc_hdr, ent);
 }
 EXPORT_SYMBOL(cmd_db_read_aux_data);
 
-/**
- * cmd_db_read_aux_data_len - Get the length of the auxiliary data stored in DB.
- *
- * @id: Resource to retrieve AUX Data.
- *
- * Return: size on success, 0 on error
- */
-size_t cmd_db_read_aux_data_len(const char *id)
-{
-	int ret;
-	const struct entry_header *ent;
-
-	ret = cmd_db_get_header(id, &ent, NULL);
-
-	return ret < 0 ? 0 : le16_to_cpu(ent->len);
-}
-EXPORT_SYMBOL(cmd_db_read_aux_data_len);
-
 /**
  * cmd_db_read_slave_id - Get the slave ID for a given resource address
  *
diff --git a/include/soc/qcom/cmd-db.h b/include/soc/qcom/cmd-db.h
index 578180cbc134..af9722223925 100644
--- a/include/soc/qcom/cmd-db.h
+++ b/include/soc/qcom/cmd-db.h
@@ -18,9 +18,7 @@ enum cmd_db_hw_type {
 #if IS_ENABLED(CONFIG_QCOM_COMMAND_DB)
 u32 cmd_db_read_addr(const char *resource_id);
 
-int cmd_db_read_aux_data(const char *resource_id, u8 *data, size_t len);
-
-size_t cmd_db_read_aux_data_len(const char *resource_id);
+const void *cmd_db_read_aux_data(const char *resource_id, size_t *len);
 
 enum cmd_db_hw_type cmd_db_read_slave_id(const char *resource_id);
 
@@ -29,12 +27,8 @@ int cmd_db_ready(void);
 static inline u32 cmd_db_read_addr(const char *resource_id)
 { return 0; }
 
-static inline int cmd_db_read_aux_data(const char *resource_id, u8 *data,
-				       size_t len)
-{ return -ENODEV; }
-
-static inline size_t cmd_db_read_aux_data_len(const char *resource_id)
-{ return -ENODEV; }
+static inline const void *cmd_db_read_aux_data(const char *resource_id, size_t *len)
+{ return ERR_PTR(-ENODEV); }
 
 static inline enum cmd_db_hw_type cmd_db_read_slave_id(const char *resource_id)
 { return -ENODEV; }
-- 
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