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82b9713ce8
Debugging the SPI CS issue with kernel 5.10 resulted in a better understanding for the root cause and a proper patch with a better explanation. Exchange the old hack patch with a more efficient (and upstreamable) solution. Signed-off-by: David Bauer <mail@david-bauer.net>
90 lines
2.9 KiB
Diff
90 lines
2.9 KiB
Diff
From 4b7d7f85abac1e7ad9e8b745694e470f0729f527 Mon Sep 17 00:00:00 2001
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From: David Bauer <mail@david-bauer.net>
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Date: Wed, 3 Mar 2021 17:11:34 +0100
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Subject: [PATCH] spi: sync up initial chipselect state
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When initially probing the SPI slave device, the call for disabling an
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SPI device without the SPI_CS_HIGH flag is not applied, as the
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condition for checking whether or not the state to be applied equals the
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one currently set evaluates to true.
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This however might not necessarily be the case, as the chipselect might
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be active.
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Add a force flag to spi_set_cs which allows to override this
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early access condition. Set it to false everywhere except when called
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from spi_setup to sync up the initial CS state.
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Fixes commit d40f0b6f2e21 ("spi: Avoid setting the chip select if we don't
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need to")
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Signed-off-by: David Bauer <mail@david-bauer.net>
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---
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drivers/spi/spi.c | 16 ++++++++--------
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1 file changed, 8 insertions(+), 8 deletions(-)
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--- a/drivers/spi/spi.c
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+++ b/drivers/spi/spi.c
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@@ -787,7 +787,7 @@ int spi_register_board_info(struct spi_b
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/*-------------------------------------------------------------------------*/
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-static void spi_set_cs(struct spi_device *spi, bool enable)
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+static void spi_set_cs(struct spi_device *spi, bool enable, bool force)
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{
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bool enable1 = enable;
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@@ -795,7 +795,7 @@ static void spi_set_cs(struct spi_device
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* Avoid calling into the driver (or doing delays) if the chip select
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* isn't actually changing from the last time this was called.
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*/
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- if ((spi->controller->last_cs_enable == enable) &&
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+ if (!force && (spi->controller->last_cs_enable == enable) &&
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(spi->controller->last_cs_mode_high == (spi->mode & SPI_CS_HIGH)))
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return;
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@@ -1243,7 +1243,7 @@ static int spi_transfer_one_message(stru
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struct spi_statistics *statm = &ctlr->statistics;
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struct spi_statistics *stats = &msg->spi->statistics;
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- spi_set_cs(msg->spi, true);
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+ spi_set_cs(msg->spi, true, false);
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SPI_STATISTICS_INCREMENT_FIELD(statm, messages);
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SPI_STATISTICS_INCREMENT_FIELD(stats, messages);
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@@ -1311,9 +1311,9 @@ fallback_pio:
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&msg->transfers)) {
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keep_cs = true;
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} else {
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- spi_set_cs(msg->spi, false);
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+ spi_set_cs(msg->spi, false, false);
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_spi_transfer_cs_change_delay(msg, xfer);
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- spi_set_cs(msg->spi, true);
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+ spi_set_cs(msg->spi, true, false);
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}
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}
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@@ -1322,7 +1322,7 @@ fallback_pio:
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out:
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if (ret != 0 || !keep_cs)
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- spi_set_cs(msg->spi, false);
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+ spi_set_cs(msg->spi, false, false);
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if (msg->status == -EINPROGRESS)
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msg->status = ret;
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@@ -3400,11 +3400,11 @@ int spi_setup(struct spi_device *spi)
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*/
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status = 0;
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- spi_set_cs(spi, false);
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+ spi_set_cs(spi, false, true);
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pm_runtime_mark_last_busy(spi->controller->dev.parent);
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pm_runtime_put_autosuspend(spi->controller->dev.parent);
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} else {
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- spi_set_cs(spi, false);
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+ spi_set_cs(spi, false, true);
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}
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mutex_unlock(&spi->controller->io_mutex);
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