[PATCH v3 0/2] qcom: remove memcpy()ing from cmd-db driver

[PATCH v3 0/2] qcom: remove memcpy()ing from cmd-db driver

[Stephen Boyd]

A couple patches for the cmd-db code to not do any more copying
of memory. Instead, we'll just hand out pointers to things
inside cmd-db. 

Changes from v2:
 * Consolidated GPU code some more per Jordan's suggestion

Changes from v1:
 * Fixed patch#2 for GPU wreckage

Cc: Mahesh Sivasubramanian <msivasub@codeaurora.org>
Cc: Lina Iyer <ilina@codeaurora.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Evan Green <evgreen@chromium.org>
Cc: Jordan Crouse <jcrouse@codeaurora.org>
Cc: Rob Clark <robdclark@gmail.com>

Stephen Boyd (2):
  soc: qcom: cmd-db: Remove memcpy()ing from cmd_db_get_header()
  soc: qcom: cmd-db: Stop memcpy()ing in cmd_db_read_aux_data()

 drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 54 ++++++----------
 drivers/soc/qcom/cmd-db.c             | 93 +++++++++------------------
 include/soc/qcom/cmd-db.h             | 12 +---
 3 files changed, 51 insertions(+), 108 deletions(-)

-- 
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[PATCH v3 1/2] soc: qcom: cmd-db: Remove memcpy()ing from cmd_db_get_header()

[Stephen Boyd]

The cmd_db_get_header() function is a static local function that doesn't
need to copy anything from one place to another. Instead, it can just
point into the region by returning pointers to what we're looking for.
If we do that, we should mark what we're returning as const so that code
can't modify cmd-db without an obvious cast.

Cc: Mahesh Sivasubramanian <msivasub@codeaurora.org>
Cc: Lina Iyer <ilina@codeaurora.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Evan Green <evgreen@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---
 drivers/soc/qcom/cmd-db.c | 60 +++++++++++++++++----------------------
 1 file changed, 26 insertions(+), 34 deletions(-)

diff --git a/drivers/soc/qcom/cmd-db.c b/drivers/soc/qcom/cmd-db.c
index a6f646295f06..5c9cc6824891 100644
--- a/drivers/soc/qcom/cmd-db.c
+++ b/drivers/soc/qcom/cmd-db.c
@@ -101,8 +101,7 @@ static bool cmd_db_magic_matches(const struct cmd_db_header *header)
 
 static struct cmd_db_header *cmd_db_header;
 
-
-static inline void *rsc_to_entry_header(struct rsc_hdr *hdr)
+static inline const void *rsc_to_entry_header(const struct rsc_hdr *hdr)
 {
 	u16 offset = le16_to_cpu(hdr->header_offset);
 
@@ -110,7 +109,7 @@ static inline void *rsc_to_entry_header(struct rsc_hdr *hdr)
 }
 
 static inline void *
-rsc_offset(struct rsc_hdr *hdr, struct entry_header *ent)
+rsc_offset(const struct rsc_hdr *hdr, const struct entry_header *ent)
 {
 	u16 offset = le16_to_cpu(hdr->data_offset);
 	u16 loffset = le16_to_cpu(ent->offset);
@@ -134,11 +133,11 @@ int cmd_db_ready(void)
 }
 EXPORT_SYMBOL(cmd_db_ready);
 
-static int cmd_db_get_header(const char *id, struct entry_header *eh,
-			     struct rsc_hdr *rh)
+static int cmd_db_get_header(const char *id, const struct entry_header **eh,
+			     const struct rsc_hdr **rh)
 {
-	struct rsc_hdr *rsc_hdr;
-	struct entry_header *ent;
+	const struct rsc_hdr *rsc_hdr;
+	const struct entry_header *ent;
 	int ret, i, j;
 	u8 query[8];
 
@@ -146,9 +145,6 @@ static int cmd_db_get_header(const char *id, struct entry_header *eh,
 	if (ret)
 		return ret;
 
-	if (!eh || !rh)
-		return -EINVAL;
-
 	/* Pad out query string to same length as in DB */
 	strncpy(query, id, sizeof(query));
 
@@ -159,14 +155,13 @@ static int cmd_db_get_header(const char *id, struct entry_header *eh,
 
 		ent = rsc_to_entry_header(rsc_hdr);
 		for (j = 0; j < le16_to_cpu(rsc_hdr->cnt); j++, ent++) {
-			if (memcmp(ent->id, query, sizeof(ent->id)) == 0)
-				break;
-		}
-
-		if (j < le16_to_cpu(rsc_hdr->cnt)) {
-			memcpy(eh, ent, sizeof(*ent));
-			memcpy(rh, rsc_hdr, sizeof(*rh));
-			return 0;
+			if (memcmp(ent->id, query, sizeof(ent->id)) == 0) {
+				if (eh)
+					*eh = ent;
+				if (rh)
+					*rh = rsc_hdr;
+				return 0;
+			}
 		}
 	}
 
@@ -186,12 +181,11 @@ static int cmd_db_get_header(const char *id, struct entry_header *eh,
 u32 cmd_db_read_addr(const char *id)
 {
 	int ret;
-	struct entry_header ent;
-	struct rsc_hdr rsc_hdr;
+	const struct entry_header *ent;
 
-	ret = cmd_db_get_header(id, &ent, &rsc_hdr);
+	ret = cmd_db_get_header(id, &ent, NULL);
 
-	return ret < 0 ? 0 : le32_to_cpu(ent.addr);
+	return ret < 0 ? 0 : le32_to_cpu(ent->addr);
 }
 EXPORT_SYMBOL(cmd_db_read_addr);
 
@@ -207,8 +201,8 @@ EXPORT_SYMBOL(cmd_db_read_addr);
 int cmd_db_read_aux_data(const char *id, u8 *data, size_t len)
 {
 	int ret;
-	struct entry_header ent;
-	struct rsc_hdr rsc_hdr;
+	const struct entry_header *ent;
+	const struct rsc_hdr *rsc_hdr;
 	u16 ent_len;
 
 	if (!data)
@@ -218,12 +212,12 @@ int cmd_db_read_aux_data(const char *id, u8 *data, size_t len)
 	if (ret)
 		return ret;
 
-	ent_len = le16_to_cpu(ent.len);
+	ent_len = le16_to_cpu(ent->len);
 	if (len < ent_len)
 		return -EINVAL;
 
 	len = min_t(u16, ent_len, len);
-	memcpy(data, rsc_offset(&rsc_hdr, &ent), len);
+	memcpy(data, rsc_offset(rsc_hdr, ent), len);
 
 	return len;
 }
@@ -239,12 +233,11 @@ EXPORT_SYMBOL(cmd_db_read_aux_data);
 size_t cmd_db_read_aux_data_len(const char *id)
 {
 	int ret;
-	struct entry_header ent;
-	struct rsc_hdr rsc_hdr;
+	const struct entry_header *ent;
 
-	ret = cmd_db_get_header(id, &ent, &rsc_hdr);
+	ret = cmd_db_get_header(id, &ent, NULL);
 
-	return ret < 0 ? 0 : le16_to_cpu(ent.len);
+	return ret < 0 ? 0 : le16_to_cpu(ent->len);
 }
 EXPORT_SYMBOL(cmd_db_read_aux_data_len);
 
@@ -258,15 +251,14 @@ EXPORT_SYMBOL(cmd_db_read_aux_data_len);
 enum cmd_db_hw_type cmd_db_read_slave_id(const char *id)
 {
 	int ret;
-	struct entry_header ent;
-	struct rsc_hdr rsc_hdr;
+	const struct entry_header *ent;
 	u32 addr;
 
-	ret = cmd_db_get_header(id, &ent, &rsc_hdr);
+	ret = cmd_db_get_header(id, &ent, NULL);
 	if (ret < 0)
 		return CMD_DB_HW_INVALID;
 
-	addr = le32_to_cpu(ent.addr);
+	addr = le32_to_cpu(ent->addr);
 	return (addr >> SLAVE_ID_SHIFT) & SLAVE_ID_MASK;
 }
 EXPORT_SYMBOL(cmd_db_read_slave_id);
-- 
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[PATCH v3 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. Updating the only user of this code
shows that making this change allows us to remove a function and put the
lookup where the user is.

Cc: Mahesh Sivasubramanian <msivasub@codeaurora.org>
Cc: Lina Iyer <ilina@codeaurora.org>
Cc: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: Evan Green <evgreen@chromium.org>
Cc: Jordan Crouse <jcrouse@codeaurora.org>
Cc: Rob Clark <robdclark@gmail.com>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
---
 drivers/gpu/drm/msm/adreno/a6xx_gmu.c | 54 ++++++++++-----------------
 drivers/soc/qcom/cmd-db.c             | 43 ++++-----------------
 include/soc/qcom/cmd-db.h             | 12 ++----
 3 files changed, 30 insertions(+), 79 deletions(-)

diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
index bbb8126ec5c5..dd1cb55949b6 100644
--- a/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
+++ b/drivers/gpu/drm/msm/adreno/a6xx_gmu.c
@@ -859,26 +859,6 @@ static int a6xx_gmu_memory_probe(struct a6xx_gmu *gmu)
 	return ret;
 }
 
-/* Get the list of RPMh voltage levels from cmd-db */
-static int a6xx_gmu_rpmh_arc_cmds(const char *id, void *vals, 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);
-
-	/*
-	 * The data comes back as an array of unsigned shorts so adjust the
-	 * count accordingly
-	 */
-	return len >> 1;
-}
-
 /* Return the 'arc-level' for the given frequency */
 static u32 a6xx_gmu_get_arc_level(struct device *dev, unsigned long freq)
 {
@@ -906,11 +886,25 @@ 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)
+		unsigned long *freqs, int freqs_count, const char *id)
 {
 	int i, j;
+	const u16 *pri, *sec;
+	size_t pri_count, sec_count;
+
+	pri = cmd_db_read_aux_data(id, &pri_count);
+	/*
+	 * The data comes back as an array of unsigned shorts so adjust the
+	 * count accordingly
+	 */
+	pri_count >>= 1;
+	if (!pri_count)
+		return -EINVAL;
+
+	sec = cmd_db_read_aux_data("mx.lvl", &sec_count);
+	sec_count >>= 1;
+	if (!sec_count)
+		return -EINVAL;
 
 	/* Construct a vote for each frequency */
 	for (i = 0; i < freqs_count; i++) {
@@ -969,25 +963,15 @@ static int a6xx_gmu_rpmh_votes_init(struct a6xx_gmu *gmu)
 	struct a6xx_gpu *a6xx_gpu = container_of(gmu, struct a6xx_gpu, gmu);
 	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
 	struct msm_gpu *gpu = &adreno_gpu->base;
-
-	u16 gx[16], cx[16], mx[16];
-	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));
-
 	/* Build the GX votes */
 	ret = a6xx_gmu_rpmh_arc_votes_init(&gpu->pdev->dev, gmu->gx_arc_votes,
-		gmu->gpu_freqs, gmu->nr_gpu_freqs,
-		gx, gxcount, mx, mxcount);
+		gmu->gpu_freqs, gmu->nr_gpu_freqs, "gfx.lvl");
 
 	/* Build the CX votes */
 	ret |= a6xx_gmu_rpmh_arc_votes_init(gmu->dev, gmu->cx_arc_votes,
-		gmu->gmu_freqs, gmu->nr_gmu_freqs,
-		cx, cxcount, mx, mxcount);
+		gmu->gmu_freqs, gmu->nr_gmu_freqs, "cx.lvl");
 
 	return ret;
 }
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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