2018-08-15 06:35:17

by Chuanhua Han

Subject: [PATCH] mtd: m25p80: consider max message size in m25p80_read when use the spi_mem_xx() API

Consider a message size limit when calculating the maximum amount
of data that can be read.

Signed-off-by: Chuanhua Han <[email protected]>
---
drivers/mtd/devices/m25p80.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index e84563d..87efa56 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -128,7 +128,12 @@ static ssize_t m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;

while (remaining) {
- op.data.nbytes = remaining < UINT_MAX ? remaining : UINT_MAX;
+ op.data.nbytes = min3(remaining,
+ spi_max_transfer_size(flash->spimem->spi),
+ spi_max_message_size(flash->spimem->spi) -
+ sizeof(op.cmd.opcode) -
+ op.addr.nbytes -
+ op.dummy.nbytes);
ret = spi_mem_adjust_op_size(flash->spimem, &op);
if (ret)
return ret;
--
2.7.4

2018-08-16 10:16:56

by Boris Brezillon

Subject: Re: [PATCH] mtd: m25p80: consider max message size in m25p80_read when use the spi_mem_xx() API

Hi Chuanhua,

On Wed, 15 Aug 2018 14:33:43 +0800
Chuanhua Han <[email protected]> wrote:

> Consider a message size limit when calculating the maximum amount
> of data that can be read.
>
> Signed-off-by: Chuanhua Han <[email protected]>
> ---
> drivers/mtd/devices/m25p80.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
> index e84563d..87efa56 100644
> --- a/drivers/mtd/devices/m25p80.c
> +++ b/drivers/mtd/devices/m25p80.c
> @@ -128,7 +128,12 @@ static ssize_t m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
> op.dummy.nbytes = (nor->read_dummy * op.dummy.buswidth) / 8;
>
> while (remaining) {
> - op.data.nbytes = remaining < UINT_MAX ? remaining : UINT_MAX;
> + op.data.nbytes = min3(remaining,
> + spi_max_transfer_size(flash->spimem->spi),
> + spi_max_message_size(flash->spimem->spi) -
> + sizeof(op.cmd.opcode) -
> + op.addr.nbytes -
> + op.dummy.nbytes);

Nope, this sort of things should go in the SPI controller driver
->adjust_op_size() hook or directly in spi_mem_adjust_op_size() if it's
generic enough (which doesn't seem to be the case since your not
counting the opcode, addr and dummy bytes in the message length).

Regards,

Boris