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Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.9.0 Subject: Re: [PATCH 3/3] spi: s3c64xx: support interrupt based pio mode Content-Language: en-US To: Mark Brown Cc: Krzysztof Kozlowski , Andi Shyti , Alim Akhtar , Rob Herring , linux-spi@vger.kernel.org, linux-samsung-soc@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Chanho Park From: Jaewon Kim In-Reply-To: <61a67466-3467-4f71-bc27-d660e37c08ac@sirena.org.uk> Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrLJsWRmVeSWpSXmKPExsWy7bCmhW6msk6KwfOrxhYP5m1js1j84zmT xdSHT9gsLu/Xtph/5Byrxd7XW9ktNj2+xmpxedccNosZ5/cxWTR+vMlu0br3CLsDt8f1JZ+Y PTat6mTzuHNtD5vH5iX1Hn1bVjF6fN4kF8AWlW2TkZqYklqkkJqXnJ+SmZduq+QdHO8cb2pm YKhraGlhrqSQl5ibaqvk4hOg65aZA3SdkkJZYk4pUCggsbhYSd/Opii/tCRVISO/uMRWKbUg JafAvECvODG3uDQvXS8vtcTK0MDAyBSoMCE743C/VMEutoplj1+xNDC2s3YxcnJICJhIzNwz Hcjm4hAS2MEoMXfie0YI5xOjxLt7b5lAqoQEPjNK3HihC9OxbdU5FoiiXYwSr+58gHJeM0q0 rexgBKniFbCTOL9rKjOIzSKgItH3tB0qLihxcuYTFhBbVCBKou/2JrA7hAXcJXat+g9Wzywg LnHryXywzSICyhJXv+8FW8As8JFJ4tbMSWAJNgFtie/rF4M1cwo4SqyY3MIC0Swvsf3tHGaQ BgmBpRwSH+a9ZIK420Wi/cU3KFtY4tXxLewQtpTE53d72SDsbIn26X+gIVMhcXHDbKi4scSs ZyAfcAAt0JRYv0sfxJQAOu7ILai1fBIdh/+yQ4R5JTrahCAa1STuTz0HNURGYtKRlVAHeEj8 mfiaeQKj4iykUJmF5PtZSJ6ZhbB3ASPLKkax1ILi3PTUYqMCE3hcJ+fnbmIEp1stjx2Ms99+ 0DvEyMTBeIhRgoNZSYRXtUsrRYg3JbGyKrUoP76oNCe1+BCjKTBuJjJLiSbnAxN+Xkm8oYml gYmZmaG5kamBuZI478cO5RQhgfTEktTs1NSC1CKYPiYOTqkGJgOfd3zuK099cVz/T5XnNs+7 pnnf103Jzve4uWZhYqpp1IvkAynbFfI3e1l3asXnT03bKPH57Ca26/Y39E4oFPBsO321YvNC nf1+Z6Y1mHCujTfzr5au8Sz2uXz9i1u+79n+68pfXt7oWGn+/O072eK/eRvaJz5jqtH6HiFk yaidFtqRmPL89O4im+Wh7Pfkot6Emb5znG3UnMmrX/d99eJo54fuj778X3co8YTiUeNdHzKC Nsy5W31o9tFaxqIZW+3imGqDbTm9/7j/Kl5Q9fBAhPdVJo4TS16JOEx9O0/hsOaUv987SyZM 1f2+8I/vZGfJNAnX2fKJut2hG1bJMtw91plYonx40SUj7dvO05RYijMSDbWYi4oTAZqiHNZA BAAA X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFupjkeLIzCtJLcpLzFFi42LZdlhJXjdDWSfFYF2bvsWDedvYLBb/eM5k MfXhEzaLy/u1LeYfOcdqsff1VnaLTY+vsVpc3jWHzWLG+X1MFo0fb7JbtO49wu7A7XF9ySdm j02rOtk87lzbw+axeUm9R9+WVYwenzfJBbBFcdmkpOZklqUW6dslcGUc7pcq2MVWsezxK5YG xnbWLkZODgkBE4ltq86xdDFycQgJ7GCUaFt2gRkiISOx/FkfG4QtLHG/5QgrRNFLRonepTNZ QBK8AnYS53dNBWtgEVCR6HvazggRF5Q4OfMJWI2oQJTE5wMt7CC2sIC7xK5V/8HqmQXEJW49 mc8EYosIKEtc/b6XBSL+kUli0gRxiGX/GCVubvkIdiqbgLbE9/WLwWxOAUeJFZNboBrMJLq2 djFC2PIS29/OYZ7AKDQLyR2zkOybhaRlFpKWBYwsqxglUwuKc9Nziw0LjPJSy/WKE3OLS/PS 9ZLzczcxgqNMS2sH455VH/QOMTJxMB5ilOBgVhLhVe3SShHiTUmsrEotyo8vKs1JLT7EKM3B oiTOe6HrZLyQQHpiSWp2ampBahFMlomDU6qBKfzy9tr84C+LN5p7qDSl3shP+9ne8L7zqm2m tayprNTyZLttX4L28M72E5+5cfvdYMNyCR8FBqunQTzPa2NTw45uDjuUpF8m0Be0b/OX26te qb1fFKX7iInvqs5x2eWnDTXZlbbtWun/SXvCoktvQ8ytl+o+byh/NperVPLO0X3d7Hdc5+w7 c/6A0i7B6Avv7J8b2Z2c9OTaV+O2Cr7v86Qap6vk+X19GRysm1Jxc6KTnczZlAcC+R4y3L9e SD+anO026ej8kL8LrxesuzVNPnGPUN75lMygexxeP3rjVj/ceui88HuhV8US4uo3vn1aFGeT r37EtGNp36Uf5/8XLZaYEVX2TFS6Rzvq+YV4DSWW4oxEQy3mouJEAIV+6achAwAA X-CMS-MailID: 20230404131728epcas2p251e43101498d4ad7591a39ce710c60f7 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: AUTO_CONFIDENTIAL CMS-TYPE: 102P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20230404061409epcas2p2b12a9cac014907e3930795cb67cb6040 References: <20230404060011.108561-1-jaewon02.kim@samsung.com> <20230404060011.108561-4-jaewon02.kim@samsung.com> <61a67466-3467-4f71-bc27-d660e37c08ac@sirena.org.uk> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello Mark, On 23. 4. 4. 21:58, Mark Brown wrote: > On Tue, Apr 04, 2023 at 03:00:11PM +0900, Jaewon Kim wrote: > >> This patch adds IRQ based PIO mode instead of cpu polling. >> By using the FIFO trigger level, interrupts are received. >> CPU consumption is reduced in PIO mode because registers are not >> constantly checked. > Is there some lower limit where it's still worth using polling, for > example for just one or two bytes like a register address? Taking an > interrupt isn't free... I did not considers lower limit. According to your review, interrupt seems to be called too often. However, It can't prevent the CPU utilization going to 100% during spi transmission. We will give more consideration and deliver a better solution to the next patch version. Thanks Jaewon Kim