123 lines
4.1 KiB
Diff
123 lines
4.1 KiB
Diff
From afbc6c9f890bd3d877451138b2ffd5bd19bfdf61 Mon Sep 17 00:00:00 2001
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From: detule <ogjoneski@gmail.com>
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Date: Tue, 2 Oct 2018 04:10:08 -0400
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Subject: [PATCH] vchiq_2835_arm: Implement a DMA pool for small bulk
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transfers (#2699)
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During a bulk transfer we request a DMA allocation to hold the
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scatter-gather list. Most of the time, this allocation is small
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(<< PAGE_SIZE), however it can be requested at a high enough frequency
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to cause fragmentation and/or stress the CMA allocator (think time
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spent in compaction here, or during allocations elsewhere).
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Implement a pool to serve up small DMA allocations, falling back
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to a coherent allocation if the request is greater than
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VCHIQ_DMA_POOL_SIZE.
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Signed-off-by: Oliver Gjoneski <ogjoneski@gmail.com>
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---
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.../interface/vchiq_arm/vchiq_2835_arm.c | 36 ++++++++++++++++---
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1 file changed, 32 insertions(+), 4 deletions(-)
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--- a/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
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+++ b/drivers/staging/vc04_services/interface/vchiq_arm/vchiq_2835_arm.c
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@@ -7,6 +7,7 @@
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#include <linux/interrupt.h>
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#include <linux/pagemap.h>
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#include <linux/dma-mapping.h>
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+#include <linux/dmapool.h>
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#include <linux/io.h>
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#include <linux/platform_device.h>
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#include <linux/uaccess.h>
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@@ -29,6 +30,8 @@
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#define BELL0 0x00
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#define BELL2 0x08
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+#define VCHIQ_DMA_POOL_SIZE PAGE_SIZE
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+
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struct vchiq_2835_state {
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int inited;
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struct vchiq_arm_state arm_state;
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@@ -38,6 +41,7 @@ struct vchiq_pagelist_info {
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struct pagelist *pagelist;
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size_t pagelist_buffer_size;
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dma_addr_t dma_addr;
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+ bool is_from_pool;
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enum dma_data_direction dma_dir;
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unsigned int num_pages;
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unsigned int pages_need_release;
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@@ -58,6 +62,7 @@ static void __iomem *g_regs;
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* of 32.
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*/
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static unsigned int g_cache_line_size = 32;
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+static struct dma_pool *g_dma_pool;
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static unsigned int g_use_36bit_addrs = 0;
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static unsigned int g_fragments_size;
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static char *g_fragments_base;
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@@ -182,6 +187,13 @@ int vchiq_platform_init(struct platform_
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g_dev = dev;
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g_dma_dev = dma_dev ?: dev;
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+ g_dma_pool = dmam_pool_create("vchiq_scatter_pool", dev,
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+ VCHIQ_DMA_POOL_SIZE, g_cache_line_size,
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+ 0);
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+ if (!g_dma_pool) {
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+ dev_err(dev, "failed to create dma pool");
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+ return -ENOMEM;
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+ }
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vchiq_log_info(vchiq_arm_log_level,
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"vchiq_init - done (slots %pK, phys %pad)",
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@@ -314,8 +326,14 @@ cleanup_pagelistinfo(struct vchiq_pageli
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if (pagelistinfo->pages_need_release)
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unpin_user_pages(pagelistinfo->pages, pagelistinfo->num_pages);
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- dma_free_coherent(g_dev, pagelistinfo->pagelist_buffer_size,
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- pagelistinfo->pagelist, pagelistinfo->dma_addr);
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+ if (pagelistinfo->is_from_pool) {
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+ dma_pool_free(g_dma_pool, pagelistinfo->pagelist,
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+ pagelistinfo->dma_addr);
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+ } else {
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+ dma_free_coherent(g_dev, pagelistinfo->pagelist_buffer_size,
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+ pagelistinfo->pagelist,
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+ pagelistinfo->dma_addr);
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+ }
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}
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/* There is a potential problem with partial cache lines (pages?)
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@@ -336,6 +354,7 @@ create_pagelist(char *buf, char __user *
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u32 *addrs;
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unsigned int num_pages, offset, i, k;
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int actual_pages;
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+ bool is_from_pool;
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size_t pagelist_size;
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struct scatterlist *scatterlist, *sg;
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int dma_buffers;
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@@ -365,8 +384,16 @@ create_pagelist(char *buf, char __user *
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/* Allocate enough storage to hold the page pointers and the page
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* list
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*/
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- pagelist = dma_alloc_coherent(g_dev, pagelist_size, &dma_addr,
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- GFP_KERNEL);
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+ if (pagelist_size > VCHIQ_DMA_POOL_SIZE) {
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+ pagelist = dma_alloc_coherent(g_dev,
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+ pagelist_size,
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+ &dma_addr,
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+ GFP_KERNEL);
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+ is_from_pool = false;
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+ } else {
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+ pagelist = dma_pool_alloc(g_dma_pool, GFP_KERNEL, &dma_addr);
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+ is_from_pool = true;
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+ }
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vchiq_log_trace(vchiq_arm_log_level, "%s - %pK", __func__, pagelist);
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@@ -387,6 +414,7 @@ create_pagelist(char *buf, char __user *
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pagelistinfo->pagelist = pagelist;
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pagelistinfo->pagelist_buffer_size = pagelist_size;
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pagelistinfo->dma_addr = dma_addr;
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+ pagelistinfo->is_from_pool = is_from_pool;
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pagelistinfo->dma_dir = (type == PAGELIST_WRITE) ?
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DMA_TO_DEVICE : DMA_FROM_DEVICE;
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pagelistinfo->num_pages = num_pages;
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