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mtd: spi-nor: Fix Cadence QSPI page fault kernel panic 

The current Cadence QSPI driver caused a kernel panic sporadically
when writing to QSPI. The problem was caused by writing more bytes
than needed because the QSPI operated on 4 bytes at a time.
<snip>
[   11.202044] Unable to handle kernel paging request at virtual address bffd3000
[   11.209254] pgd = e463054d
[   11.211948] [bffd3000] *pgd=2fffb811, *pte=00000000, *ppte=00000000
[   11.218202] Internal error: Oops: 7 [#1] SMP ARM
[   11.222797] Modules linked in:
[   11.225844] CPU: 1 PID: 1317 Comm: systemd-hwdb Not tainted 4.17.7-d0c45cd44a8f
[   11.235796] Hardware name: Altera SOCFPGA Arria10
[   11.240487] PC is at __raw_writesl+0x70/0xd4
[   11.244741] LR is at cqspi_write+0x1a0/0x2cc
</snip>
On a page boundary limit the number of bytes copied from the tx buffer
to remain within the page.

This patch uses a temporary buffer to hold the 4 bytes to write and then
copies only the bytes required from the tx buffer.

Reported-by: Adrian Amborzewicz <adrian.ambrozewicz@intel.com>
Signed-off-by: Thor Thayer <thor.thayer@linux.intel.com>
Signed-off-by: Boris Brezillon <boris.brezillon@bootlin.com>
This commit is contained in:
Thor Thayer 2018-11-16 08:25:49 -06:00 committed by Boris Brezillon
parent 33bf5519ae
commit a6a66f80c8
1 changed files with 16 additions and 3 deletions
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19
drivers/mtd/spi-nor/cadence-quadspi.c
View File

@ -644,9 +644,23 @@ static int cqspi_indirect_write_execute(struct spi_nor *nor, loff_t to_addr,
ndelay(cqspi->wr_delay);
while (remaining > 0) {
size_t write_words, mod_bytes;
write_bytes = remaining > page_size ? page_size : remaining;
iowrite32_rep(cqspi->ahb_base, txbuf,
DIV_ROUND_UP(write_bytes, 4));
write_words = write_bytes / 4;
mod_bytes = write_bytes % 4;
/* Write 4 bytes at a time then single bytes. */
if (write_words) {
iowrite32_rep(cqspi->ahb_base, txbuf, write_words);
txbuf += (write_words * 4);
}
if (mod_bytes) {
unsigned int temp = 0xFFFFFFFF;
memcpy(&temp, txbuf, mod_bytes);
iowrite32(temp, cqspi->ahb_base);
txbuf += mod_bytes;
}
if (!wait_for_completion_timeout(&cqspi->transfer_complete,
msecs_to_jiffies(CQSPI_TIMEOUT_MS))) {
@ -655,7 +669,6 @@ static int cqspi_indirect_write_execute(struct spi_nor *nor, loff_t to_addr,
goto failwr;
}
txbuf += write_bytes;
remaining -= write_bytes;
if (remaining > 0)