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(217-133-54-93.static.clienti.tiscali.it. [217.133.54.93]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-3632d8562a1sm1993532f8f.2.2024.06.19.02.17.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Jun 2024 02:17:56 -0700 (PDT) From: Alberto Secondi To: hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com Cc: iommu@lists.linux.dev, linux-kernel@vger.kernel.org, alberto.secondi@abinsula.com, Davide Salaris Subject: [PATCH] New config added to handle 64-bit systems with 32-bit DMA support Date: Wed, 19 Jun 2024 11:17:37 +0200 Message-Id: <20240619091737.669040-1-albertosecondi@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Alberto Secondi The kernel assumes that 64-bit systems have 64-bit DMA support through CONFIG_ARCH_DMA_ADDR_T_64BIT. This is not always true; for example, several iMX8 systems (verified on iMX8MM and iMX8MP) have DMA with only 32-bit supp= ort. This results in several drivers requesting DMA_BIT_MASK(64), which causes malfunctions, particularly when systems have more than 3GB of DRAM (verified with the lan743x driver and iMX8 systems with 4GB of DRAM). Therefore, a new config ARCH_64BIT_HAS_DMA32_ONLY was added to manage 64-bit systems with 32= -bit DMA, which adjusts DMA_BIT_MASK(n) accordingly. Signed-off-by: Alberto Secondi Co-developed-by: Davide Salaris --- include/linux/dma-mapping.h | 4 ++++ kernel/dma/Kconfig | 8 ++++++++ 2 files changed, 12 insertions(+) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index f693aafe221f..629220a777e3 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -74,7 +74,11 @@ */ #define DMA_MAPPING_ERROR (~(dma_addr_t)0) =20 +#ifdef CONFIG_ARCH_64BIT_HAS_DMA32_ONLY +#define DMA_BIT_MASK(n) (((n) > 32) ? ((1ULL<<(32))-1) : ((1ULL<<(n))-1)) +#else #define DMA_BIT_MASK(n) (((n) =3D=3D 64) ? ~0ULL : ((1ULL<<(n))-1)) +#endif =20 #ifdef CONFIG_DMA_API_DEBUG void debug_dma_mapping_error(struct device *dev, dma_addr_t dma_addr); diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig index c06e56be0ca1..0a27eafed808 100644 --- a/kernel/dma/Kconfig +++ b/kernel/dma/Kconfig @@ -36,6 +36,14 @@ config NEED_DMA_MAP_STATE config ARCH_DMA_ADDR_T_64BIT def_bool 64BIT || PHYS_ADDR_T_64BIT =20 +config ARCH_64BIT_HAS_DMA32_ONLY + bool "64bit System has DMA32 only" + depends on ARCH_DMA_ADDR_T_64BIT + default n + help + This enables forcing the maximum DMA_BIT_MASK to 32 bits for + 64-bit systems that have DMA support limited to 32 bits. + config ARCH_HAS_DMA_SET_MASK bool =20 --=20 2.34.1