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From: Florian Fainelli <f.fainelli@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Sasha Levin <sashal@kernel.org>,
	stable@vger.kernel.org, Florian Fainelli <f.fainelli@gmail.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
	Russell King <linux@armlinux.org.uk>,
	Mike Rapoport <rppt@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Ard Biesheuvel <ardb@kernel.org>,
	Max Filippov <jcmvbkbc@gmail.com>,
	linux-arm-kernel@lists.infradead.org (moderated list:ARM PORT)
Subject: [PATCH stable 5.10] ARM: Qualify enabling of swiotlb_init()
Date: Wed, 22 Sep 2021 17:14:24 -0700	[thread overview]
Message-ID: <20210923001425.414046-1-f.fainelli@gmail.com> (raw)

commit fcf044891c84e38fc90eb736b818781bccf94e38 upstream

We do not need a SWIOTLB unless we have DRAM that is addressable beyond
the arm_dma_limit. Compare max_pfn with arm_dma_pfn_limit to determine
whether we do need a SWIOTLB to be initialized.

Fixes: ad3c7b18c5b3 ("arm: use swiotlb for bounce buffering on LPAE configs")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
---
 arch/arm/mm/init.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mm/init.c b/arch/arm/mm/init.c
index d54d69cf1732..75f3ab531bdf 100644
--- a/arch/arm/mm/init.c
+++ b/arch/arm/mm/init.c
@@ -378,7 +378,11 @@ static void __init free_highpages(void)
 void __init mem_init(void)
 {
 #ifdef CONFIG_ARM_LPAE
-	swiotlb_init(1);
+	if (swiotlb_force == SWIOTLB_FORCE ||
+	    max_pfn > arm_dma_pfn_limit)
+		swiotlb_init(1);
+	else
+		swiotlb_force = SWIOTLB_NO_FORCE;
 #endif
 
 	set_max_mapnr(pfn_to_page(max_pfn) - mem_map);
-- 
2.25.1


             reply	other threads:[~2021-09-23  0:14 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-23  0:14 Florian Fainelli [this message]
2021-09-23  8:06 ` Greg Kroah-Hartman

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