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Subject[PATCH] dell_rbu: stop abusing the DMA API
Date
For some odd reason dell_rbu actually seems to want the physical and
not a bus address for the allocated buffer. Lets assume that actually
is correct given that it is BIOS-related and that is a good source
of insanity. In that case we should not use dma_alloc_coherent with
a NULL device to allocate memory, but use GFP_DMA32 to stay under
the 32-bit BIOS limit.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
drivers/platform/x86/dell_rbu.c | 52 ++++++++++-----------------------
1 file changed, 15 insertions(+), 37 deletions(-)

diff --git a/drivers/platform/x86/dell_rbu.c b/drivers/platform/x86/dell_rbu.c
index ccefa84f7305..fba7d96c1714 100644
--- a/drivers/platform/x86/dell_rbu.c
+++ b/drivers/platform/x86/dell_rbu.c
@@ -59,7 +59,6 @@ static struct _rbu_data {
unsigned long image_update_buffer_size;
unsigned long bios_image_size;
int image_update_ordernum;
- int dma_alloc;
spinlock_t lock;
unsigned long packet_read_count;
unsigned long num_packets;
@@ -89,7 +88,6 @@ static struct packet_data packet_data_head;

static struct platform_device *rbu_device;
static int context;
-static dma_addr_t dell_rbu_dmaaddr;

static void init_packet_head(void)
{
@@ -380,12 +378,8 @@ static void img_update_free(void)
*/
memset(rbu_data.image_update_buffer, 0,
rbu_data.image_update_buffer_size);
- if (rbu_data.dma_alloc == 1)
- dma_free_coherent(NULL, rbu_data.bios_image_size,
- rbu_data.image_update_buffer, dell_rbu_dmaaddr);
- else
- free_pages((unsigned long) rbu_data.image_update_buffer,
- rbu_data.image_update_ordernum);
+ free_pages((unsigned long) rbu_data.image_update_buffer,
+ rbu_data.image_update_ordernum);

/*
* Re-initialize the rbu_data variables after a free
@@ -394,7 +388,6 @@ static void img_update_free(void)
rbu_data.image_update_buffer = NULL;
rbu_data.image_update_buffer_size = 0;
rbu_data.bios_image_size = 0;
- rbu_data.dma_alloc = 0;
}

/*
@@ -410,10 +403,8 @@ static void img_update_free(void)
static int img_update_realloc(unsigned long size)
{
unsigned char *image_update_buffer = NULL;
- unsigned long rc;
unsigned long img_buf_phys_addr;
int ordernum;
- int dma_alloc = 0;

/*
* check if the buffer of sufficient size has been
@@ -444,36 +435,23 @@ static int img_update_realloc(unsigned long size)

ordernum = get_order(size);
image_update_buffer =
- (unsigned char *) __get_free_pages(GFP_KERNEL, ordernum);
-
- img_buf_phys_addr =
- (unsigned long) virt_to_phys(image_update_buffer);
-
- if (img_buf_phys_addr > BIOS_SCAN_LIMIT) {
- free_pages((unsigned long) image_update_buffer, ordernum);
- ordernum = -1;
- image_update_buffer = dma_alloc_coherent(NULL, size,
- &dell_rbu_dmaaddr, GFP_KERNEL);
- dma_alloc = 1;
- }
-
- spin_lock(&rbu_data.lock);
-
- if (image_update_buffer != NULL) {
- rbu_data.image_update_buffer = image_update_buffer;
- rbu_data.image_update_buffer_size = size;
- rbu_data.bios_image_size =
- rbu_data.image_update_buffer_size;
- rbu_data.image_update_ordernum = ordernum;
- rbu_data.dma_alloc = dma_alloc;
- rc = 0;
- } else {
+ (unsigned char *)__get_free_pages(GFP_DMA32, ordernum);
+ if (!image_update_buffer) {
pr_debug("Not enough memory for image update:"
"size = %ld\n", size);
- rc = -ENOMEM;
+ return -ENOMEM;
}

- return rc;
+ img_buf_phys_addr = (unsigned long)virt_to_phys(image_update_buffer);
+ if (WARN_ON_ONCE(img_buf_phys_addr > BIOS_SCAN_LIMIT))
+ return -EINVAL; /* can't happen per defintion */
+
+ spin_lock(&rbu_data.lock);
+ rbu_data.image_update_buffer = image_update_buffer;
+ rbu_data.image_update_buffer_size = size;
+ rbu_data.bios_image_size = rbu_data.image_update_buffer_size;
+ rbu_data.image_update_ordernum = ordernum;
+ return 0;
}

static ssize_t read_packet_data(char *buffer, loff_t pos, size_t count)
--
2.20.1
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