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[108.51.35.162]) by smtp.googlemail.com with ESMTPSA id q20sm5956338qtn.80.2020.11.09.06.49.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 09 Nov 2020 06:49:20 -0800 (PST) Subject: Re: [PATCH 02/32] spi: dw: Add support for 32-bits ctrlr0 layout To: Andy Shevchenko Cc: Serge Semin , Damien Le Moal , Palmer Dabbelt , linux-riscv@lists.infradead.org, Rob Herring , Frank Rowand , devicetree , Mark Brown , linux-spi , Stephen Boyd , linux-clk , Linus Walleij , "open list:GPIO SUBSYSTEM" , Philipp Zabel References: <20201107081420.60325-1-damien.lemoal@wdc.com> <20201107081420.60325-3-damien.lemoal@wdc.com> <20201109142529.tt5ojjyn36vd3ohe@mobilestation> <6dc6d52e-a39d-c351-5280-71b9e8eafe37@gmail.com> From: Sean Anderson Autocrypt: addr=seanga2@gmail.com; prefer-encrypt=mutual; keydata= mQENBFe74PkBCACoLC5Zq2gwrDcCkr+EPGsT14bsxrW07GiYzQhLCgwnPdEpgU95pXltbFhw 46GfyffABWxHKO2x+3L1S6ZxC5AiKbYXo7lpnTBYjamPWYouz+VJEVjUx9aaSEByBah5kX6a lKFZWNbXLAJh+dE1HFaMi3TQXXaInaREc+aO1F7fCa2zNE75ja+6ah8L4TPRFZ2HKQzve0/Y GXtoRw97qmnm3U36vKWT/m2AiLF619F4T1mHvlfjyd9hrVwjH5h/2rFyroXVXBZHGA9Aj8eN F2si35dWSZlIwXkNu9bXp0/pIu6FD0bI+BEkD5S7aH1G1iAcMFi5Qq2RNa041DfQSDDHABEB AAG0K1NlYW4gR2FsbGFnaGVyIEFuZGVyc29uIDxzZWFuZ2EyQGdtYWlsLmNvbT6JAVcEEwEK AEECGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4ACGQEWIQSQYR1bzo1I0gPoYCg+6I/stKEQ bgUCXT+S2AUJB2TlXwAKCRA+6I/stKEQbhNOB/9ooea0hU9Sgh7PBloU6CgaC5mlqPLB7NTp +JkB+nh3Fqhk+qLZwzEynnuDLl6ESpVHIc0Ym1lyF4gT3DsrlGT1h0Gzw7vUwd1+ZfN0CuIx Rn861U/dAUjvbtN5kMBqOI4/5ea+0r7MACcIVnKF/wMXBD8eypHsorT2sJTzwZ6DRCNP70C5 N1ahpqqNmXe0uLdP0pu55JCqhrGw2SinkRMdWyhSxT56uNwIVHGhLTqH7Q4t1N6G1EH626qa SvIJsWlNpll6Y3AYLDw2/Spw/hqieS2PQ/Ky3rPZnvJt7/aSNYsKoFGX0yjkH67Uq8Lx0k1L w8jpXnbEPQN3A2ZJCbeM Message-ID: <7e8bba71-763e-2e09-88d2-d736a56a6920@gmail.com> Date: Mon, 9 Nov 2020 09:49:19 -0500 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org On 11/9/20 9:41 AM, Andy Shevchenko wrote: > On Mon, Nov 9, 2020 at 4:40 PM Andy Shevchenko > wrote: >> >> On Mon, Nov 9, 2020 at 4:34 PM Sean Anderson wrote: >>> On 11/9/20 9:25 AM, Serge Semin wrote: >>>> On Sat, Nov 07, 2020 at 05:13:50PM +0900, Damien Le Moal wrote: >> >> ... >> >>>> Are you sure they have been moved from [0, 3] to [16, 20]? I don't have the >>>> manual for the 4.0x version of the core, but according to this patch: >>>> https://patchwork.kernel.org/project/spi-devel-general/patch/1575907443-26377-7-git-send-email-wan.ahmad.zainie.wan.mohamad@intel.com/ >>>> it has been ok to use the lowest four bits for DFS setting. Is the commit >>>> message misleading there? >>> >>> This commit message is a truncated version of [1]. >> >> I don't see how they are related. I think this commit message is specifically taken from v3 of that patch [2]. However, I had not gotten a chance to have a look at the datasheet at that point, so it is a bit misleading (e.g. showing dfs for devices with SSI_MAX_XFER_SIZE=32, even though it is all zeros for those devices). In any case, the diagram is taken from that patch. [2] https://patchwork.ozlabs.org/project/uboot/patch/20200914153503.91983-7-seanga2@gmail.com/ > > For DW_ssi v1.x DFS is always for transfers up to 32-bit. Do you mean DWC_ssi? > >>> Importantly, DFS is >>> valid when SSI_MAX_XFER_SIZE=16. When it =32, then DFS_32 must be used >>> (since DFS is constant 0xF). Since SSI_MAX_XFER_SIZE is a synthesis >>> parameter, there exist devices where DFS must be used, and also where >>> DFS_32 must be used. >>> >>> [1] https://patchwork.ozlabs.org/project/uboot/patch/20201016225755.302659-10-seanga2@gmail.com/ > > >