From: Alain Volmat <alain.volmat@foss.st.com>
To: <broonie@kernel.org>, <amelie.delaunay@foss.st.com>
Cc: <mcoquelin.stm32@gmail.com>, <alexandre.torgue@foss.st.com>,
<linux-spi@vger.kernel.org>,
<linux-stm32@st-md-mailman.stormreply.com>,
<linux-arm-kernel@lists.infradead.org>,
<linux-kernel@vger.kernel.org>, <fabrice.gasnier@foss.st.com>,
<alain.volmat@foss.st.com>, <antonio.borneo@foss.st.com>
Subject: [PATCH] spi: stm32: drop devres version of spi_register_master
Date: Fri, 12 Mar 2021 11:34:46 +0100 [thread overview]
Message-ID: <1615545286-5395-1-git-send-email-alain.volmat@foss.st.com> (raw)
From: Antonio Borneo <antonio.borneo@foss.st.com>
A call to spi_unregister_master() triggers calling remove()
for all the spi devices binded to the spi master.
Some spi device driver requires to "talk" with the spi device
during the remove(), e.g.:
- a LCD panel like drivers/gpu/drm/panel/panel-lg-lg4573.c
will turn off the backlighting sending a command over spi.
This implies that the spi master must be fully functional when
spi_unregister_master() is called, either if it is called
explicitly in the master's remove() code or implicitly by the
devres framework.
Devres calls devres_release_all() to release all the resources
"after" the remove() of the spi master driver (check code of
__device_release_driver() in drivers/base/dd.c).
If the spi master driver has an empty remove() then there would
be no issue; the devres_release_all() will release everything
in reverse order w.r.t. probe().
But if code in spi master driver remove() disables the spi or
makes it not functional (like in this spi-stm32), then devres
cannot be used safely for unregistering the spi master and the
binded spi devices.
Replace devm_spi_register_master() with spi_register_master()
and add spi_unregister_master() as first action in remove().
Fixes: dcbe0d84dfa5 ("spi: add driver for STM32 SPI controller")
Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Signed-off-by: Alain Volmat <alain.volmat@foss.st.com>
---
drivers/spi/spi-stm32.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/drivers/spi/spi-stm32.c b/drivers/spi/spi-stm32.c
index 25c076461011..97cf3a2d4180 100644
--- a/drivers/spi/spi-stm32.c
+++ b/drivers/spi/spi-stm32.c
@@ -1929,7 +1929,7 @@ static int stm32_spi_probe(struct platform_device *pdev)
pm_runtime_set_active(&pdev->dev);
pm_runtime_enable(&pdev->dev);
- ret = devm_spi_register_master(&pdev->dev, master);
+ ret = spi_register_master(master);
if (ret) {
dev_err(&pdev->dev, "spi master registration failed: %d\n",
ret);
@@ -1960,6 +1960,7 @@ static int stm32_spi_remove(struct platform_device *pdev)
struct spi_master *master = platform_get_drvdata(pdev);
struct stm32_spi *spi = spi_master_get_devdata(master);
+ spi_unregister_master(master);
spi->cfg->disable(spi);
if (master->dma_tx)
--
2.17.1
next reply other threads:[~2021-03-12 10:35 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 10:34 Alain Volmat [this message]
2021-03-12 20:25 ` [PATCH] spi: stm32: drop devres version of spi_register_master Mark Brown
2021-03-16 21:17 ` Lukas Wunner
2021-03-18 7:22 ` Alain Volmat
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