[PATCH v2] mmc: pxamci: Simplify pxamci_probe() error handling using devm APIs

Rakuram Eswaran
2025-10-14T18:47:55Z

This patch refactors pxamci_probe() to use devm-managed resource
allocation (e.g. devm_dma_request_chan()) and dev_err_probe() for
improved readability and automatic cleanup on probe failure.

This eliminates redundant NULL assignments and manual release logic.

This issue was originally reported by Smatch:
drivers/mmc/host/pxamci.c:709 pxamci_probe() warn: passing zero to 'PTR_ERR'

The warning occurred because a pointer was set to NULL before using
PTR_ERR(), leading to PTR_ERR(0) and an incorrect 0 return value.
This refactor eliminates that condition while improving overall
error handling robustness.

Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202510041841.pRlunIfl-lkp@intel.com/
Fixes: 58c40f3faf742c ("mmc: pxamci: Use devm_mmc_alloc_host() helper")
Suggested-by: Uwe Kleine-König <u.kleine-koenig@baylibre.com>
Signed-off-by: Rakuram Eswaran <rakuram.e96@gmail.com>
---

Changes since v1:
Following Uwe Kleine-König’s suggestion:
- Replaced dma_request_chan() with devm_dma_request_chan() to make DMA
channel allocation devm-managed and avoid manual release paths.
- Used dev_err_probe() for improved error reporting and consistent
probe failure handling.
- Removed redundant NULL assignments and obsolete goto-based cleanup logic.
- Updated commit message to better describe the intent of the change.

Testing note:
I do not have access to appropriate hardware for runtime testing.
Any help verifying on actual hardware would be appreciated.

Build and Analysis:
This patch was compiled against the configuration file reported by
0day CI in the above link (config: s390-randconfig-r071-20251004) using
`s390x-linux-gnu-gcc (Ubuntu 14.2.0-19ubuntu2) 14.2.0`.

Static analysis was performed with Smatch to ensure the reported warning
no longer reproduces after applying this fix.

Command used for verification:
ARCH=s390 CROSS_COMPILE=s390x-linux-gnu- \
~/project/smatch/smatch_scripts/kchecker ./drivers/mmc/host/pxamci.c

drivers/mmc/host/pxamci.c | 57 +++++++++++++++------------------------
1 file changed, 21 insertions(+), 36 deletions(-)

diff --git a/drivers/mmc/host/pxamci.c b/drivers/mmc/host/pxamci.c
index 26d03352af63..d03388f64934 100644
--- a/drivers/mmc/host/pxamci.c
+++ b/drivers/mmc/host/pxamci.c
@@ -652,11 +652,14 @@ static int pxamci_probe(struct platform_device *pdev)
host->clkrt = CLKRT_OFF;

host->clk = devm_clk_get(dev, NULL);
- if (IS_ERR(host->clk)) {
- host->clk = NULL;
- return PTR_ERR(host->clk);
- }
+ if (IS_ERR(host->clk))
+ return dev_err_probe(dev, PTR_ERR(host->clk),
+ "Failed to acquire clock\n");

+ /*
+ * Note that the return value of clk_get_rate() is only valid
+ * if the clock is enabled.
+ */
host->clkrate = clk_get_rate(host->clk);

/*
@@ -703,46 +706,36 @@ static int pxamci_probe(struct platform_device *pdev)

platform_set_drvdata(pdev, mmc);

- host->dma_chan_rx = dma_request_chan(dev, "rx");
- if (IS_ERR(host->dma_chan_rx)) {
- host->dma_chan_rx = NULL;
+ host->dma_chan_rx = devm_dma_request_chan(dev, "rx");
+ if (IS_ERR(host->dma_chan_rx))
return dev_err_probe(dev, PTR_ERR(host->dma_chan_rx),
"unable to request rx dma channel\n");
- }

- host->dma_chan_tx = dma_request_chan(dev, "tx");
- if (IS_ERR(host->dma_chan_tx)) {
- dev_err(dev, "unable to request tx dma channel\n");
- ret = PTR_ERR(host->dma_chan_tx);
- host->dma_chan_tx = NULL;
- goto out;
- }
+ host->dma_chan_tx = devm_dma_request_chan(dev, "tx");
+ if (IS_ERR(host->dma_chan_tx))
+ return dev_err_probe(dev, PTR_ERR(host->dma_chan_tx),
+ "unable to request tx dma channel\n");

if (host->pdata) {
host->detect_delay_ms = host->pdata->detect_delay_ms;

host->power = devm_gpiod_get_optional(dev, "power", GPIOD_OUT_LOW);
- if (IS_ERR(host->power)) {
- ret = PTR_ERR(host->power);
- dev_err(dev, "Failed requesting gpio_power\n");
- goto out;
- }
+ if (IS_ERR(host->power))
+ return dev_err_probe(dev, PTR_ERR(host->power),
+ "Failed requesting gpio_power\n");

/* FIXME: should we pass detection delay to debounce? */
ret = mmc_gpiod_request_cd(mmc, "cd", 0, false, 0);
- if (ret && ret != -ENOENT) {
- dev_err(dev, "Failed requesting gpio_cd\n");
- goto out;
- }
+ if (ret && ret != -ENOENT)
+ return dev_err_probe(dev, ret, "Failed requesting gpio_cd\n");

if (!host->pdata->gpio_card_ro_invert)
mmc->caps2 |= MMC_CAP2_RO_ACTIVE_HIGH;

ret = mmc_gpiod_request_ro(mmc, "wp", 0, 0);
- if (ret && ret != -ENOENT) {
- dev_err(dev, "Failed requesting gpio_ro\n");
- goto out;
- }
+ if (ret && ret != -ENOENT)
+ return dev_err_probe(dev, ret, "Failed requesting gpio_ro\n");
+
if (!ret)
host->use_ro_gpio = true;

@@ -759,16 +752,8 @@ static int pxamci_probe(struct platform_device *pdev)
if (ret) {
if (host->pdata && host->pdata->exit)
host->pdata->exit(dev, mmc);
- goto out;
}

- return 0;
-
-out:
- if (host->dma_chan_rx)
- dma_release_channel(host->dma_chan_rx);
- if (host->dma_chan_tx)
- dma_release_channel(host->dma_chan_tx);
return ret;
}

--
2.48.1