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Date: Wed, 24 Feb 2010 14:53:56 +0100
From: Wolfgang Mües <wolfgang.mues@...rswald.de>
To: Andrew Victor <linux@...im.org.za>
Cc: linux-kernel@...r.kernel.org
Subject: [PATCH] Bugfixing and improvement of the AT91 MCI driver
Andrew,
as we are working on a project regarding AT91SAM9260 and using the
MCI interface for SD/SDHC data transfer, we are forced to make a
series of bugfixes and improvements to the AT91 MCI driver:
- Fix a buf in the dmabuf pointer calculation.
- Use a fixed DMA buffer instead of allocating a DMA buffer
each time a data transfer is requested.
- Fix address error in kunmap_atomic().
- Use the dma buffer also for reads, because we found
that double buffering PDC was NOT working, and we need
a solution which allows bigger stream sizes.
- Use dmac_flush_range() because flush_dcache_page()
was not OK if more than one page is transferred.
- Extend card timeout to 2s because some cards need it.
- Extend card detect time to 500ms (usefull if the user
is inserting the card gentle into the slot).
- Fill in the mmc->max_ variables to allow the IO elevator
to do the job. Without these variables filled in,
each IO transfer is limited to 4096 bytes, which is limiting
transfer speed and - most important - is triggering
ACCELLERATED WEAR-OUT of the flash sectors of the card
(because the card has to do a lot of partial sector
erases).
We have tested this driver which a lot of SD and SDHC cards
and we think the driver is ready for production use now.
For reads, we get about 90% of the expected maximum calculated
speed (from the clock frequency). For writes, we get about 50%.
As we are using a slightly older kernel, I have ported this
patch to latest 2.6.33 by hand. So please take care to compile
and look for compile-time errors. I've done my very best.
Signed-off-by: Wolfgang Muees <wolfgang.mues@...rswald.de>
---
diff -ur linux-2.6.33-rc8-original/drivers/mmc/host/at91_mci.c linux-2.6.33-rc8-at91/drivers/mmc/host/at91_mci.c
--- linux-2.6.33-rc8-original/drivers/mmc/host/at91_mci.c 2010-02-12 20:07:45.000000000 +0100
+++ linux-2.6.33-rc8-at91/drivers/mmc/host/at91_mci.c 2010-02-24 14:21:46.838590913 +0100
@@ -88,6 +88,10 @@
#define at91_mci_read(host, reg) __raw_readl((host)->baseaddr + (reg))
#define at91_mci_write(host, reg, val) __raw_writel((val), (host)->baseaddr + (reg))
+#define MCI_BLKSIZE 512
+#define MCI_MAXBLKSIZE 4095
+#define MCI_BLKATONCE 256
+#define MCI_BUFSIZE (MCI_BLKSIZE * MCI_BLKATONCE)
/*
* Low level type for this driver
@@ -227,11 +231,13 @@
for (index = 0; index < (amount / 4); index++)
*dmabuf++ = swab32(sgbuffer[index]);
} else {
- memcpy(dmabuf, sgbuffer, amount);
- dmabuf += amount;
+ char *tmpv = (char *)dmabuf;
+ memcpy(tmpv, sgbuffer, amount);
+ tmpv += amount;
+ dmabuf = (unsigned *)tmpv;
}
- kunmap_atomic(sgbuffer, KM_BIO_SRC_IRQ);
+ kunmap_atomic(((void*)sgbuffer)-sg->offset, KM_BIO_SRC_IRQ);
if (size == 0)
break;
@@ -245,80 +251,14 @@
}
/*
- * Prepare a dma read
- */
-static void at91_mci_pre_dma_read(struct at91mci_host *host)
-{
- int i;
- struct scatterlist *sg;
- struct mmc_command *cmd;
- struct mmc_data *data;
-
- pr_debug("pre dma read\n");
-
- cmd = host->cmd;
- if (!cmd) {
- pr_debug("no command\n");
- return;
- }
-
- data = cmd->data;
- if (!data) {
- pr_debug("no data\n");
- return;
- }
-
- for (i = 0; i < 2; i++) {
- /* nothing left to transfer */
- if (host->transfer_index >= data->sg_len) {
- pr_debug("Nothing left to transfer (index = %d)\n", host->transfer_index);
- break;
- }
-
- /* Check to see if this needs filling */
- if (i == 0) {
- if (at91_mci_read(host, ATMEL_PDC_RCR) != 0) {
- pr_debug("Transfer active in current\n");
- continue;
- }
- }
- else {
- if (at91_mci_read(host, ATMEL_PDC_RNCR) != 0) {
- pr_debug("Transfer active in next\n");
- continue;
- }
- }
-
- /* Setup the next transfer */
- pr_debug("Using transfer index %d\n", host->transfer_index);
-
- sg = &data->sg[host->transfer_index++];
- pr_debug("sg = %p\n", sg);
-
- sg->dma_address = dma_map_page(NULL, sg_page(sg), sg->offset, sg->length, DMA_FROM_DEVICE);
-
- pr_debug("dma address = %08X, length = %d\n", sg->dma_address, sg->length);
-
- if (i == 0) {
- at91_mci_write(host, ATMEL_PDC_RPR, sg->dma_address);
- at91_mci_write(host, ATMEL_PDC_RCR, (data->blksz & 0x3) ? sg->length : sg->length / 4);
- }
- else {
- at91_mci_write(host, ATMEL_PDC_RNPR, sg->dma_address);
- at91_mci_write(host, ATMEL_PDC_RNCR, (data->blksz & 0x3) ? sg->length : sg->length / 4);
- }
- }
-
- pr_debug("pre dma read done\n");
-}
-
-/*
* Handle after a dma read
*/
static void at91_mci_post_dma_read(struct at91mci_host *host)
{
struct mmc_command *cmd;
struct mmc_data *data;
+ unsigned int len, i, size;
+ unsigned *dmabuf = host->buffer;
pr_debug("post dma read\n");
@@ -334,42 +274,40 @@
return;
}
- while (host->in_use_index < host->transfer_index) {
- struct scatterlist *sg;
-
- pr_debug("finishing index %d\n", host->in_use_index);
-
- sg = &data->sg[host->in_use_index++];
+ size = data->blksz * data->blocks;
+ len = data->sg_len;
+
+ at91_mci_write(host, AT91_MCI_IDR, AT91_MCI_ENDRX);
+ at91_mci_write(host, AT91_MCI_IER, AT91_MCI_RXBUFF);
- pr_debug("Unmapping page %08X\n", sg->dma_address);
+ for (i = 0; i < len; i++) {
+ struct scatterlist *sg;
+ int amount;
+ unsigned int *sgbuffer;
- dma_unmap_page(NULL, sg->dma_address, sg->length, DMA_FROM_DEVICE);
+ sg = &data->sg[i];
+ sgbuffer = kmap_atomic(sg_page(sg), KM_BIO_SRC_IRQ) + sg->offset;
+ amount = min(size, sg->length);
+ size -= amount;
+
if (cpu_is_at91rm9200()) { /* AT91RM9200 errata */
- unsigned int *buffer;
- int index;
-
- /* Swap the contents of the buffer */
- buffer = kmap_atomic(sg_page(sg), KM_BIO_SRC_IRQ) + sg->offset;
- pr_debug("buffer = %p, length = %d\n", buffer, sg->length);
-
- for (index = 0; index < (sg->length / 4); index++)
- buffer[index] = swab32(buffer[index]);
- kunmap_atomic(buffer, KM_BIO_SRC_IRQ);
+ int index;
+ for (index = 0; index < (amount / 4); index++)
+ sgbuffer[index] = swab32(*dmabuf++);
+ } else {
+ char *tmpv = (char *)dmabuf;
+ memcpy(sgbuffer, tmpv, amount);
+ tmpv += amount;
+ dmabuf = (unsigned *)tmpv;
}
- flush_dcache_page(sg_page(sg));
-
- data->bytes_xfered += sg->length;
- }
-
- /* Is there another transfer to trigger? */
- if (host->transfer_index < data->sg_len)
- at91_mci_pre_dma_read(host);
- else {
- at91_mci_write(host, AT91_MCI_IDR, AT91_MCI_ENDRX);
- at91_mci_write(host, AT91_MCI_IER, AT91_MCI_RXBUFF);
+ kunmap_atomic(((void*)sgbuffer)-sg->offset, KM_BIO_SRC_IRQ);
+ dmac_flush_range ((void*)sgbuffer, ((void*)sgbuffer)+amount);
+ data->bytes_xfered += amount;
+ if (size == 0)
+ break;
}
pr_debug("post dma read done\n");
@@ -602,10 +540,14 @@
/*
* Handle a read
*/
- host->buffer = NULL;
host->total_length = 0;
- at91_mci_pre_dma_read(host);
+ at91_mci_write(host, ATMEL_PDC_RPR, host->physical_address);
+ at91_mci_write(host, ATMEL_PDC_RCR, (data->blksz & 0x3) ?
+ (blocks * block_length) : (blocks * block_length) / 4);
+ at91_mci_write(host, ATMEL_PDC_RNPR, 0);
+ at91_mci_write(host, ATMEL_PDC_RNCR, 0);
+
ier = AT91_MCI_ENDRX /* | AT91_MCI_RXBUFF */;
}
else {
@@ -621,20 +563,8 @@
if (host->total_length < 12)
host->total_length = 12;
- host->buffer = kmalloc(host->total_length, GFP_KERNEL);
- if (!host->buffer) {
- pr_debug("Can't alloc tx buffer\n");
- cmd->error = -ENOMEM;
- mmc_request_done(host->mmc, host->request);
- return;
- }
-
at91_mci_sg_to_dma(host, data);
- host->physical_address = dma_map_single(NULL,
- host->buffer, host->total_length,
- DMA_TO_DEVICE);
-
pr_debug("Transmitting %d bytes\n", host->total_length);
at91_mci_write(host, ATMEL_PDC_TPR, host->physical_address);
@@ -701,14 +631,6 @@
cmd->resp[2] = at91_mci_read(host, AT91_MCI_RSPR(2));
cmd->resp[3] = at91_mci_read(host, AT91_MCI_RSPR(3));
- if (host->buffer) {
- dma_unmap_single(NULL,
- host->physical_address, host->total_length,
- DMA_TO_DEVICE);
- kfree(host->buffer);
- host->buffer = NULL;
- }
-
pr_debug("Status = %08X/%08x [%08X %08X %08X %08X]\n",
status, at91_mci_read(host, AT91_MCI_SR),
cmd->resp[0], cmd->resp[1], cmd->resp[2], cmd->resp[3]);
@@ -754,7 +676,8 @@
host->request = mrq;
host->flags = 0;
- mod_timer(&host->timer, jiffies + HZ);
+ /* more than 1s timeout seen with takeMS sdhc cards */
+ mod_timer(&host->timer, jiffies + 2 * HZ);
at91_mci_process_next(host);
}
@@ -942,7 +865,8 @@
pr_debug("****** Resetting SD-card bus width ******\n");
at91_mci_write(host, AT91_MCI_SDCR, at91_mci_read(host, AT91_MCI_SDCR) & ~AT91_MCI_SDCBUS);
}
- mmc_detect_change(host->mmc, msecs_to_jiffies(100));
+ /* 0.5s is needed here because of early switch firing. */
+ mmc_detect_change(host->mmc, msecs_to_jiffies(500));
}
return IRQ_HANDLED;
}
@@ -1008,12 +932,15 @@
mmc->ocr_avail = MMC_VDD_32_33 | MMC_VDD_33_34;
mmc->caps = MMC_CAP_SDIO_IRQ;
- mmc->max_blk_size = 4095;
- mmc->max_blk_count = mmc->max_req_size;
+ mmc->max_blk_size = MCI_MAXBLKSIZE;
+ mmc->max_blk_count = MCI_BLKATONCE;
+ mmc->max_phys_segs = MCI_BLKATONCE;
+ mmc->max_hw_segs = MCI_BLKATONCE;
+ mmc->max_req_size = MCI_BUFSIZE;
+ mmc->max_seg_size = MCI_BUFSIZE;
host = mmc_priv(mmc);
host->mmc = mmc;
- host->buffer = NULL;
host->bus_mode = 0;
host->board = pdev->dev.platform_data;
if (host->board->wire4) {
@@ -1024,6 +951,13 @@
" - using 1 wire\n");
}
+ host->buffer = dma_alloc_coherent(&pdev->dev, MCI_BUFSIZE, &host->physical_address, GFP_KERNEL);
+ if (!host->buffer){
+ ret = -ENOMEM;
+ dev_err(&pdev->dev, "Can't allocate transmit buffer\n");
+ goto fail5;
+ }
+
/*
* Reserve GPIOs ... board init code makes sure these pins are set
* up as GPIOs with the right direction (input, except for vcc)
@@ -1032,7 +966,7 @@
ret = gpio_request(host->board->det_pin, "mmc_detect");
if (ret < 0) {
dev_dbg(&pdev->dev, "couldn't claim card detect pin\n");
- goto fail5;
+ goto fail4b;
}
}
if (host->board->wp_pin) {
@@ -1132,6 +1066,9 @@
fail4:
if (host->board->det_pin)
gpio_free(host->board->det_pin);
+fail4b:
+ if (host->buffer)
+ dma_free_coherent (&pdev->dev, MCI_BUFSIZE, host->buffer, host->physical_address);
fail5:
mmc_free_host(mmc);
fail6:
@@ -1154,6 +1091,9 @@
host = mmc_priv(mmc);
+ if (host->buffer)
+ dma_free_coherent (&pdev->dev, MCI_BUFSIZE, host->buffer, host->physical_address);
+
if (host->board->det_pin) {
if (device_can_wakeup(&pdev->dev))
free_irq(gpio_to_irq(host->board->det_pin), host);
---
best regards
i. A. Wolfgang Mües
--
Auerswald Gesellschaft für Datensysteme mbH
Hardware Development
Telefon: +49 (0)5306 9219 562
Telefax: +49 (0)5306 9219 94
E-Mail: Wolfgang.Mues@...rswald.de
Web: http://www.auerswald.de
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