From: Antonio Borneo antonio.borneo@foss.st.com
[ Upstream commit 8d559a64f00b59af9cc02b803ff52f6e6880a651 ]
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 Link: https://lore.kernel.org/r/1615545286-5395-1-git-send-email-alain.volmat@foss... Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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)