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spi: Avoid using malloc() in a critical function

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In general we should avoid calling malloc() and free() repeatedly in
U-Boot lest we turn it into tianocore. In SPL this can make SPI flash
unusable since free() is often a nop and allocation space is limited.

In any case, these seems no need for malloc() since the number of bytes
is very small, perhaps less than 8.

Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes: d13f5b254a (spi: Extend the core to ease integration of SPI
	memory controllers)
This commit is contained in:
Simon Glass 2019-05-18 11:59:54 -06:00
parent 731ba3c0be
commit ca2abb75a0
1 changed files with 11 additions and 4 deletions
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15
drivers/spi/spi-mem.c
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@ -201,7 +201,6 @@ int spi_mem_exec_op(struct spi_slave *slave, const struct spi_mem_op *op)
unsigned int pos = 0;
const u8 *tx_buf = NULL;
u8 *rx_buf = NULL;
u8 *op_buf;
int op_len;
u32 flag;
int ret;
@ -338,7 +337,17 @@ int spi_mem_exec_op(struct spi_slave *slave, const struct spi_mem_op *op)
}
op_len = sizeof(op->cmd.opcode) + op->addr.nbytes + op->dummy.nbytes;
op_buf = calloc(1, op_len);
/*
* Avoid using malloc() here so that we can use this code in SPL where
* simple malloc may be used. That implementation does not allow free()
* so repeated calls to this code can exhaust the space.
*
* The value of op_len is small, since it does not include the actual
* data being sent, only the op-code and address. In fact, it should be
* possible to just use a small fixed value here instead of op_len.
*/
u8 op_buf[op_len];
op_buf[pos++] = op->cmd.opcode;
@ -382,8 +391,6 @@ int spi_mem_exec_op(struct spi_slave *slave, const struct spi_mem_op *op)
debug("%02x ", tx_buf ? tx_buf[i] : rx_buf[i]);
debug("[ret %d]\n", ret);
free(op_buf);
if (ret < 0)
return ret;
#endif /* __UBOOT__ */