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[net-next,4/4] net: ipa: relax 64-bit build requirement

Message ID 20210317222946.118125-5-elder@linaro.org
State Superseded
Headers show
Series net: ipa: support 32-bit targets | expand

Commit Message

Alex Elder March 17, 2021, 10:29 p.m. UTC 
We currently assume the IPA driver is built only for a 64 bit kernel.

When this constraint was put in place it eliminated some do_div()
calls, replacing them with the "/" and "%" operators.  We now only
use these operations on u32 and size_t objects.  In a 32-bit kernel
build, size_t will be 32 bits wide, so there remains no reason to
use do_div() for divide and modulo.

A few recent commits also fix some code that assumes that DMA
addresses are 64 bits wide.

With that, we can get rid of the 64-bit build requirement.

Signed-off-by: Alex Elder <elder@linaro.org>

---
 drivers/net/ipa/Kconfig    |  2 +-
 drivers/net/ipa/ipa_main.c | 10 ++++++++--
 2 files changed, 9 insertions(+), 3 deletions(-)

-- 
2.27.0
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Patch

diff --git a/drivers/net/ipa/Kconfig b/drivers/net/ipa/Kconfig
index b68f1289b89ef..90a90262e0d07 100644
--- a/drivers/net/ipa/Kconfig
+++ b/drivers/net/ipa/Kconfig
@@ -1,6 +1,6 @@ 
 config QCOM_IPA
 	tristate "Qualcomm IPA support"
-	depends on 64BIT && NET && QCOM_SMEM
+	depends on NET && QCOM_SMEM
 	depends on ARCH_QCOM || COMPILE_TEST
 	depends on QCOM_RPROC_COMMON || (QCOM_RPROC_COMMON=n && COMPILE_TEST)
 	select QCOM_MDT_LOADER if ARCH_QCOM
diff --git a/drivers/net/ipa/ipa_main.c b/drivers/net/ipa/ipa_main.c
index 97c1b55405cbf..d354e3e65ec50 100644
--- a/drivers/net/ipa/ipa_main.c
+++ b/drivers/net/ipa/ipa_main.c
@@ -735,8 +735,14 @@  MODULE_DEVICE_TABLE(of, ipa_match);
 static void ipa_validate_build(void)
 {
 #ifdef IPA_VALIDATE
-	/* We assume we're working on 64-bit hardware */
-	BUILD_BUG_ON(!IS_ENABLED(CONFIG_64BIT));
+	/* At one time we assumed a 64-bit build, allowing some do_div()
+	 * calls to be replaced by simple division or modulo operations.
+	 * We currently only perform divide and modulo operations on u32,
+	 * u16, or size_t objects, and of those only size_t has any chance
+	 * of being a 64-bit value.  (It should be guaranteed 32 bits wide
+	 * on a 32-bit build, but there is no harm in verifying that.)
+	 */
+	BUILD_BUG_ON(!IS_ENABLED(CONFIG_64BIT) && sizeof(size_t) != 4);
 
 	/* Code assumes the EE ID for the AP is 0 (zeroed structure field) */
 	BUILD_BUG_ON(GSI_EE_AP != 0);