From: Arnd Bergmann <arnd@arndb.de> To: Li Chen <me@linux.beauty> Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Rob Herring <robh+dt@kernel.org>, Frank Rowand <frowand.list@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, Li Chen <lchen@ambarella.com>, Linux ARM <linux-arm-kernel@lists.infradead.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, DTML <devicetree@vger.kernel.org>, Linux-MM <linux-mm@kvack.org> Subject: Re: [PATCH 4/4] sample/reserved_mem: Introduce a sample of struct page and dio support to no-map rmem Date: Mon, 11 Jul 2022 15:28:10 +0200 [thread overview] Message-ID: <CAK8P3a2Mr0ZMXGDx6htYEbBBtm4mubk-meSASJjPRK1j1O-hEA@mail.gmail.com> (raw) In-Reply-To: <20220711122459.13773-5-me@linux.beauty> On Mon, Jul 11, 2022 at 2:24 PM Li Chen <me@linux.beauty> wrote: > > From: Li Chen <lchen@ambarella.com> > > This sample driver shows how to build struct pages support to no-map rmem. > > Signed-off-by: Li Chen <lchen@ambarella.com> Not sure what a sample driver helps here if there are no actual users in-tree. It would make more sense to merge the driver that wants to actually use this first, and then add the additional feature. > Change-Id: Ie78494fa86fda40ceb73eab3b8ba505d0ad851a1 Please drop these lines, the Change-Id fields are useless in a public repository. > +/* > + * dts example > + * rmem: rmem@1 { > + * compatible = "shared-dma-pool"; > + * no-map; > + * size = <0x0 0x20000000>; > + * }; > + * perf { > + * compatible = "example,rmem"; > + * memory-region = <&rmem>; > + * }; The problem here is that the DT is meant to describe the platform in an OS independent way, so having a binding that just corresponds to a user space interface is not a good abstraction. > + vaddr = reserved_mem_memremap_pages(dev, rmem); > + if (IS_ERR_OR_NULL(vaddr)) > + return PTR_ERR(vaddr); Using IS_ERR_OR_NULL() is usually an indication of a bad interface. For the reserved_mem_memremap_pages(), you should decide whether to return NULL on error or an error pointer, but not both. Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de> To: Li Chen <me@linux.beauty> Cc: Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Rob Herring <robh+dt@kernel.org>, Frank Rowand <frowand.list@gmail.com>, Andrew Morton <akpm@linux-foundation.org>, Li Chen <lchen@ambarella.com>, Linux ARM <linux-arm-kernel@lists.infradead.org>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, DTML <devicetree@vger.kernel.org>, Linux-MM <linux-mm@kvack.org> Subject: Re: [PATCH 4/4] sample/reserved_mem: Introduce a sample of struct page and dio support to no-map rmem Date: Mon, 11 Jul 2022 15:28:10 +0200 [thread overview] Message-ID: <CAK8P3a2Mr0ZMXGDx6htYEbBBtm4mubk-meSASJjPRK1j1O-hEA@mail.gmail.com> (raw) In-Reply-To: <20220711122459.13773-5-me@linux.beauty> On Mon, Jul 11, 2022 at 2:24 PM Li Chen <me@linux.beauty> wrote: > > From: Li Chen <lchen@ambarella.com> > > This sample driver shows how to build struct pages support to no-map rmem. > > Signed-off-by: Li Chen <lchen@ambarella.com> Not sure what a sample driver helps here if there are no actual users in-tree. It would make more sense to merge the driver that wants to actually use this first, and then add the additional feature. > Change-Id: Ie78494fa86fda40ceb73eab3b8ba505d0ad851a1 Please drop these lines, the Change-Id fields are useless in a public repository. > +/* > + * dts example > + * rmem: rmem@1 { > + * compatible = "shared-dma-pool"; > + * no-map; > + * size = <0x0 0x20000000>; > + * }; > + * perf { > + * compatible = "example,rmem"; > + * memory-region = <&rmem>; > + * }; The problem here is that the DT is meant to describe the platform in an OS independent way, so having a binding that just corresponds to a user space interface is not a good abstraction. > + vaddr = reserved_mem_memremap_pages(dev, rmem); > + if (IS_ERR_OR_NULL(vaddr)) > + return PTR_ERR(vaddr); Using IS_ERR_OR_NULL() is usually an indication of a bad interface. For the reserved_mem_memremap_pages(), you should decide whether to return NULL on error or an error pointer, but not both. Arnd _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2022-07-11 13:28 UTC|newest] Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-07-11 12:24 [PATCH 0/4] add struct page and Direct I/O support to reserved memory Li Chen 2022-07-11 12:24 ` Li Chen 2022-07-11 12:24 ` [PATCH 1/4] of: add struct page support to rmem Li Chen 2022-07-11 12:24 ` Li Chen 2022-07-11 13:36 ` Arnd Bergmann 2022-07-11 13:36 ` Arnd Bergmann 2022-07-11 14:51 ` Li Chen 2022-07-11 14:51 ` Li Chen 2022-07-11 15:06 ` Arnd Bergmann 2022-07-11 15:06 ` Arnd Bergmann 2022-07-12 3:13 ` Li Chen 2022-07-12 3:13 ` Li Chen 2022-07-16 0:38 ` kernel test robot 2022-07-16 0:38 ` kernel test robot 2022-07-11 12:24 ` [PATCH 2/4] mm/sparse: skip no-map memblock check when fill_subsection_map Li Chen 2022-07-11 12:24 ` Li Chen 2022-07-11 14:53 ` David Hildenbrand 2022-07-11 14:53 ` David Hildenbrand 2022-07-12 4:23 ` Li Chen 2022-07-12 4:23 ` Li Chen 2022-07-12 7:31 ` David Hildenbrand 2022-07-12 7:31 ` David Hildenbrand 2022-07-12 9:31 ` Li Chen 2022-07-12 9:31 ` Li Chen 2022-07-14 18:45 ` kernel test robot 2022-07-14 18:45 ` kernel test robot 2022-07-11 12:24 ` [PATCH 3/4] arm64: mm: move memblock_clear_nomap after __add_pages Li Chen 2022-07-11 12:24 ` Li Chen 2022-07-11 12:24 ` [PATCH 4/4] sample/reserved_mem: Introduce a sample of struct page and dio support to no-map rmem Li Chen 2022-07-11 12:24 ` Li Chen 2022-07-11 13:28 ` Arnd Bergmann [this message] 2022-07-11 13:28 ` Arnd Bergmann 2022-07-12 0:26 ` Li Chen 2022-07-12 0:26 ` Li Chen 2022-07-12 7:50 ` Arnd Bergmann 2022-07-12 7:50 ` Arnd Bergmann 2022-07-12 9:58 ` Li Chen 2022-07-12 9:58 ` Li Chen 2022-07-12 10:08 ` Arnd Bergmann 2022-07-12 10:08 ` Arnd Bergmann 2022-07-12 10:20 ` Arnd Bergmann 2022-07-12 10:20 ` Arnd Bergmann 2022-07-12 10:55 ` Li Chen 2022-07-12 10:55 ` Li Chen 2022-07-12 12:10 ` Arnd Bergmann 2022-07-12 12:10 ` Arnd Bergmann 2022-08-04 7:17 ` Li Chen 2022-08-04 7:17 ` Li Chen 2022-08-04 8:24 ` Arnd Bergmann 2022-08-04 8:24 ` Arnd Bergmann 2022-08-04 10:07 ` Li Chen 2022-08-04 10:07 ` Li Chen 2022-08-05 14:09 ` Arnd Bergmann 2022-08-05 14:09 ` Arnd Bergmann 2022-08-05 15:28 ` David Hildenbrand 2022-08-05 15:28 ` David Hildenbrand 2022-07-11 15:01 ` [PATCH 0/4] add struct page and Direct I/O support to reserved memory Christoph Hellwig 2022-07-11 15:01 ` Christoph Hellwig 2022-07-11 16:05 ` Li Chen 2022-07-11 16:05 ` Li Chen 2022-07-11 16:09 ` Christoph Hellwig 2022-07-11 16:09 ` Christoph Hellwig 2022-07-12 0:14 ` Li Chen 2022-07-12 0:14 ` Li Chen 2022-07-18 9:26 [PATCH 1/4] of: add struct page support to rmem kernel test robot 2022-07-18 13:21 ` Dan Carpenter 2022-07-18 13:21 ` Dan Carpenter 2022-07-18 13:21 ` Dan Carpenter
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