aboutsummaryrefslogtreecommitdiffstats
path: root/target/linux/brcm2708/patches-4.19/950-0141-vchiq_2835_arm-Implement-a-DMA-pool-for-small-bulk-t.patch
blob: b246b826ec694fed29f486e7ef281bbf9852501f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
From 8a9e2054d3ecf11044136daa5644d803db486dd4 Mon Sep 17 00:00:00 2001
From: detule <ogjoneski@gmail.com>
Date: Tue, 2 Oct 2018 04:10:08 -0400
Subject: [PATCH 141/703] vchiq_2835_arm: Implement a DMA pool for small bulk
 transfers (#2699)

During a bulk transfer we request a DMA allocation to hold the
scatter-gather list.  Most of the time, this allocation is small
(<< PAGE_SIZE), however it can be requested at a high enough frequency
to cause fragmentation and/or stress the CMA allocator (think time
spent in compaction here, or during allocations elsewhere).

Implement a pool to serve up small DMA allocations, falling back
to a coherent allocation if the request is greater than
VCHIQ_DMA_POOL_SIZE.

Signed-off-by: Oliver Gjoneski <ogjoneski@gmail.com>
---
 .../interface/vchiq_arm/vchiq_2835_arm.c      | 40 +++++++++++++++----
 1 file changed, 33 insertions(+), 7 deletions(-)

--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
@@ -37,6 +37,7 @@
 #include <linux/interrupt.h>
 #include <linux/pagemap.h>
 #include <linux/dma-mapping.h>
+#include <linux/dmapool.h>
 #include <linux/io.h>
 #include <linux/platform_device.h>
 #include <linux/uaccess.h>
@@ -60,6 +61,8 @@
 #define BELL0	0x00
 #define BELL2	0x08
 
+#define VCHIQ_DMA_POOL_SIZE PAGE_SIZE
+
 struct vchiq_2835_state {
 	int inited;
 	VCHIQ_ARM_STATE_T arm_state;
@@ -69,6 +72,7 @@ struct vchiq_pagelist_info {
 	PAGELIST_T *pagelist;
 	size_t pagelist_buffer_size;
 	dma_addr_t dma_addr;
+	bool is_from_pool;
 	enum dma_data_direction dma_dir;
 	unsigned int num_pages;
 	unsigned int pages_need_release;
@@ -91,6 +95,7 @@ static void __iomem *g_regs;
  * relevant Device Tree node.
  */
 static unsigned int g_cache_line_size;
+static struct dma_pool *g_dma_pool;
 static unsigned int g_fragments_size;
 static char *g_fragments_base;
 static char *g_free_fragments;
@@ -206,6 +211,14 @@ int vchiq_platform_init(struct platform_
 	}
 
 	g_dev = dev;
+	g_dma_pool = dmam_pool_create("vchiq_scatter_pool", dev,
+				      VCHIQ_DMA_POOL_SIZE, g_cache_line_size,
+				      0);
+	if (!g_dma_pool) {
+		dev_err(dev, "failed to create dma pool");
+		return -ENOMEM;
+	}
+
 	vchiq_log_info(vchiq_arm_log_level,
 		"vchiq_init - done (slots %pK, phys %pad)",
 		vchiq_slot_zero, &slot_phys);
@@ -397,9 +410,14 @@ cleanup_pagelistinfo(struct vchiq_pageli
 		for (i = 0; i < pagelistinfo->num_pages; i++)
 			put_page(pagelistinfo->pages[i]);
 	}
-
-	dma_free_coherent(g_dev, pagelistinfo->pagelist_buffer_size,
-			  pagelistinfo->pagelist, pagelistinfo->dma_addr);
+	if (pagelistinfo->is_from_pool) {
+		dma_pool_free(g_dma_pool, pagelistinfo->pagelist,
+			      pagelistinfo->dma_addr);
+	} else {
+		dma_free_coherent(g_dev, pagelistinfo->pagelist_buffer_size,
+				  pagelistinfo->pagelist,
+				  pagelistinfo->dma_addr);
+	}
 }
 
 /* There is a potential problem with partial cache lines (pages?)
@@ -419,6 +437,7 @@ create_pagelist(char __user *buf, size_t
 	u32 *addrs;
 	unsigned int num_pages, offset, i, k;
 	int actual_pages;
+	bool is_from_pool;
 	size_t pagelist_size;
 	struct scatterlist *scatterlist, *sg;
 	int dma_buffers;
@@ -445,10 +464,16 @@ create_pagelist(char __user *buf, size_t
 	/* Allocate enough storage to hold the page pointers and the page
 	 * list
 	 */
-	pagelist = dma_zalloc_coherent(g_dev,
-				       pagelist_size,
-				       &dma_addr,
-				       GFP_KERNEL);
+	if (pagelist_size > VCHIQ_DMA_POOL_SIZE) {
+		pagelist = dma_zalloc_coherent(g_dev,
+					       pagelist_size,
+					       &dma_addr,
+					       GFP_KERNEL);
+		is_from_pool = false;
+	} else {
+		pagelist = dma_pool_zalloc(g_dma_pool, GFP_KERNEL, &dma_addr);
+		is_from_pool = true;
+	}
 
 	vchiq_log_trace(vchiq_arm_log_level, "%s - %pK", __func__, pagelist);
 
@@ -469,6 +494,7 @@ create_pagelist(char __user *buf, size_t
 	pagelistinfo->pagelist = pagelist;
 	pagelistinfo->pagelist_buffer_size = pagelist_size;
 	pagelistinfo->dma_addr = dma_addr;
+	pagelistinfo->is_from_pool = is_from_pool;
 	pagelistinfo->dma_dir =  (type == PAGELIST_WRITE) ?
 				  DMA_TO_DEVICE : DMA_FROM_DEVICE;
 	pagelistinfo->num_pages = num_pages;