[PATCH] mmc: sdhci-of-esdhc: Don't walk device-tree on every interrupt

From: Chris Packham
Date: Wed Sep 02 2020 - 00:06:52 EST


Commit b214fe592ab7 ("mmc: sdhci-of-esdhc: add erratum eSDHC7 support")
added code to check for a specific compatible string in the device-tree
on every esdhc interrupt. We know that if it's present the compatible
string will be found on the sdhc host. Instead of walking the
device-tree, go directly to the sdhc host's device and use
of_device_is_compatible().

Signed-off-by: Chris Packham <chris.packham@xxxxxxxxxxxxxxxxxxx>
---

I found this in passing while trying to track down another issue using ftrace.
I found it odd that I was seeing a lot of calls to __of_device_is_compatible()
coming from esdhc_irq() (the fact that this interrupt is going off on my board
is also odd, but that's a different story).

drivers/mmc/host/sdhci-of-esdhc.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/sdhci-of-esdhc.c b/drivers/mmc/host/sdhci-of-esdhc.c
index 7c73d243dc6c..11c8c522d623 100644
--- a/drivers/mmc/host/sdhci-of-esdhc.c
+++ b/drivers/mmc/host/sdhci-of-esdhc.c
@@ -1177,10 +1177,11 @@ static void esdhc_set_uhs_signaling(struct sdhci_host *host,

static u32 esdhc_irq(struct sdhci_host *host, u32 intmask)
{
+ struct device *dev = mmc_dev(host->mmc);
+ struct device_node *np = dev->of_node;
u32 command;

- if (of_find_compatible_node(NULL, NULL,
- "fsl,p2020-esdhc")) {
+ if (of_device_is_compatible(np, "fsl,p2020-esdhc")) {
command = SDHCI_GET_CMD(sdhci_readw(host,
SDHCI_COMMAND));
if (command == MMC_WRITE_MULTIPLE_BLOCK &&
--
2.28.0