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spi: move split xfers for CS_WORD emulation

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This moves splitting transfers for CS_WORD software emulation to the
same place where we split transfers for controller-specific reasons.

This fixes a few subtle bugs.

The calculation for maxsize was wrong for bit sizes between 17 and 24.
This is fixed by making use of spi_split_transfers_maxwords() which
already has the correct calculation.

Also, since this indirectly calls spi_res_alloc(), to avoid leaking
resources, spi_finalize_current_message() would need to be called
on all error paths in __spi_validate() and callers of __spi_validate()
would need to do the same. This is fixed by moving the call to
__spi_pump_transfer_message() where it is already splitting transfers
for other reasons and correctly releases resources in the subsequent
error paths.

Fixes: cbaa62e0094a ("spi: add software implementation for SPI_CS_WORD")
Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://lore.kernel.org/r/20240126212358.3916280-2-dlechner@baylibre.com
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
David Lechner 2024-01-26 15:23:57 -06:00 committed by Mark Brown
parent 1e942b5bb1
commit c8bec3355f
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GPG Key ID: 24D68B725D5487D0
1 changed files with 31 additions and 32 deletions
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63
drivers/spi/spi.c
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@ -1743,13 +1743,37 @@ static int __spi_pump_transfer_message(struct spi_controller *ctlr,
trace_spi_message_start(msg);
ret = spi_split_transfers_maxsize(ctlr, msg,
spi_max_transfer_size(msg->spi),
GFP_KERNEL | GFP_DMA);
if (ret) {
msg->status = ret;
spi_finalize_current_message(ctlr);
return ret;
/*
* If an SPI controller does not support toggling the CS line on each
* transfer (indicated by the SPI_CS_WORD flag) or we are using a GPIO
* for the CS line, we can emulate the CS-per-word hardware function by
* splitting transfers into one-word transfers and ensuring that
* cs_change is set for each transfer.
*/
if ((msg->spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits & SPI_CS_WORD) ||
spi_is_csgpiod(msg->spi))) {
ret = spi_split_transfers_maxwords(ctlr, msg, 1, GFP_KERNEL);
if (ret) {
msg->status = ret;
spi_finalize_current_message(ctlr);
return ret;
}
list_for_each_entry(xfer, &msg->transfers, transfer_list) {
/* Don't change cs_change on the last entry in the list */
if (list_is_last(&xfer->transfer_list, &msg->transfers))
break;
xfer->cs_change = 1;
}
} else {
ret = spi_split_transfers_maxsize(ctlr, msg,
spi_max_transfer_size(msg->spi),
GFP_KERNEL | GFP_DMA);
if (ret) {
msg->status = ret;
spi_finalize_current_message(ctlr);
return ret;
}
}
if (ctlr->prepare_message) {
@ -4061,31 +4085,6 @@ static int __spi_validate(struct spi_device *spi, struct spi_message *message)
message->spi = spi;
/*
* If an SPI controller does not support toggling the CS line on each
* transfer (indicated by the SPI_CS_WORD flag) or we are using a GPIO
* for the CS line, we can emulate the CS-per-word hardware function by
* splitting transfers into one-word transfers and ensuring that
* cs_change is set for each transfer.
*/
if ((spi->mode & SPI_CS_WORD) && (!(ctlr->mode_bits & SPI_CS_WORD) ||
spi_is_csgpiod(spi))) {
size_t maxsize = BITS_TO_BYTES(spi->bits_per_word);
int ret;
ret = spi_split_transfers_maxsize(ctlr, message, maxsize,
GFP_KERNEL);
if (ret)
return ret;
list_for_each_entry(xfer, &message->transfers, transfer_list) {
/* Don't change cs_change on the last entry in the list */
if (list_is_last(&xfer->transfer_list, &message->transfers))
break;
xfer->cs_change = 1;
}
}
/*
* Half-duplex links include original MicroWire, and ones with
* only one data pin like SPI_3WIRE (switches direction) or where