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Tue, 12 Jul 2022 09:44:43 +0900 (KST) Received: from epsmtrp2.samsung.com (unknown [182.195.40.14]) by epcas2p4.samsung.com (KnoxPortal) with ESMTPA id 20220712004443epcas2p4ed1e9ac5497517407000b08623556801~A7k5Xov-w0800008000epcas2p4O; Tue, 12 Jul 2022 00:44:43 +0000 (GMT) Received: from epsmgms1p1new.samsung.com (unknown [182.195.42.41]) by epsmtrp2.samsung.com (KnoxPortal) with ESMTP id 20220712004443epsmtrp2d4263dc594ee503be415c6af648f64b2~A7k5WZqvb2162821628epsmtrp2c; Tue, 12 Jul 2022 00:44:43 +0000 (GMT) X-AuditID: b6c32a47-5f7ff700000025aa-fd-62ccc3fbbad2 Received: from epsmtip2.samsung.com ( [182.195.34.31]) by epsmgms1p1new.samsung.com (Symantec Messaging Gateway) with SMTP id 3F.65.08905.AF3CCC26; Tue, 12 Jul 2022 09:44:42 +0900 (KST) Received: from KORCO082417 (unknown [10.229.8.121]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20220712004442epsmtip2e247ae5c2e3a0a11c3170f5ebed262d3~A7k5GirzM0309003090epsmtip2a; Tue, 12 Jul 2022 00:44:42 +0000 (GMT) From: "Chanho Park" To: "'Marek Szyprowski'" , "'Krzysztof Kozlowski'" , "'Greg Kroah-Hartman'" Cc: "'Jiri Slaby'" , "'Alim Akhtar'" , "'Hector Martin'" , "'Jaewon Kim'" , "'Vincent Whitchurch'" , =?utf-8?Q?'Ilpo_J=C3=A4rvinen'?= , , , In-Reply-To: <4fb8c922-08aa-2ee3-8073-95b8a26bf5db@samsung.com> Subject: RE: [PATCH v3] tty: serial: samsung_tty: loopback mode support Date: Tue, 12 Jul 2022 09:44:42 +0900 Message-ID: <000001d89588$936d14c0$ba473e40$@samsung.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQLzDSGin7fZbeDDkoOCu4DD8KtQ/QLMCkYfAQCTfcqrJo9MMA== Content-Language: ko X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrIJsWRmVeSWpSXmKPExsWy7bCmhe7vw2eSDOYdVrZ4MG8bm0Xz4vVs Fp07elgsdjQcYbV4N1fGYu/rrewWmx5fY7WYcX4fk8WZxb3sFmuP3GW3OH1tAbvF+W3+Djwe 19cFeGxa1cnmcefaHjaPeScDPfbPXcPusXlJvcfiZTvZPPq2rGL0+LxJLoAzKtsmIzUxJbVI ITUvOT8lMy/dVsk7ON453tTMwFDX0NLCXEkhLzE31VbJxSdA1y0zB+hcJYWyxJxSoFBAYnGx kr6dTVF+aUmqQkZ+cYmtUmpBSk6BeYFecWJucWleul5eaomVoYGBkSlQYUJ2xsu7j5kKXrNV tG14yNzAOJe1i5GDQ0LAROLQJqEuRi4OIYEdjBJzZv5lh3A+MUqcOr6eDcL5xigxe/90li5G TrCOF9O7WSESexklNk1ZzQjhvGCUmLTnBhNIFZuAvsTLjm1gVSICyxglLvYvYgFxmAWmMEuc XHuQFaSKU8BeYlbnLHYQW1jAXWJ18ztmEJtFQFXiz/VHYDavgKXEnxWbmCBsQYmTM5+A3cEs oC2xbOFrZoibFCR+Pl0GNlNEwEni5vJ1TBA1IhKzO9uYQRZLCJzhkHjYvoURosFF4vKyZ2wQ trDEq+Nb2CFsKYnP7/ZCxYslls76xATR3MAocXnbL6iEscSsZ+2MoPBjFtCUWL9LHxKUyhJH bkHdxifRcRgUkiBhXomONiGIRnWJA9thwSgr0T3nM+sERqVZSD6bheSzWUg+mIWwawEjyypG sdSC4tz01GKjAmN4dCfn525iBKdlLfcdjDPeftA7xMjEwXiIUYKDWUmE98/ZU0lCvCmJlVWp RfnxRaU5qcWHGE2BYT2RWUo0OR+YGfJK4g1NLA1MzMwMzY1MDcyVxHm9UjYkCgmkJ5akZqem FqQWwfQxcXBKNTAJV/UvDt5n6PvdcqKb9uG1q7sTb86+fPWUSJlvopZ/xZsH1n8CBXvzw3pK pm4vqekzsaqq+sUm3h7QdOtmHvsLMxl7picb6sJeTPB7oPbf6qDmN+Z/q849fPbrN9f6l6tN BG9tNPbqYDlh5fhrb5z7Et7pe55uvnbbQjC0T+/vs2aO5yvlXOYKCR9dN0/+itilr+mXvFZt Zr7/k7VqGq8v9x3HSPEv529fny/zvnhXYlN88sTjqzVrO71UUlmUe/SqOJ/mz/tplnRDaJmU WWeaMsua6Q6V39ar88qr/Lv8pk3U3mLD9PrmI5ZyGR1ZzhM3WP2pqohxnJv2cN5d07Vzz75v Kv4Xm7uRv/kNR5USS3FGoqEWc1FxIgCuPOFZVAQAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFlrLIsWRmVeSWpSXmKPExsWy7bCSvO6vw2eSDN5utrJ4MG8bm0Xz4vVs Fp07elgsdjQcYbV4N1fGYu/rrewWmx5fY7WYcX4fk8WZxb3sFmuP3GW3OH1tAbvF+W3+Djwe 19cFeGxa1cnmcefaHjaPeScDPfbPXcPusXlJvcfiZTvZPPq2rGL0+LxJLoAzissmJTUnsyy1 SN8ugSvjYNML9oKnbBWTmz+zNDBOZu1i5OSQEDCReDG9G8jm4hAS2M0oMat1PTtEQlbi2bsd ULawxP2WI1BFzxglPq26DZZgE9CXeNmxDWySiMAyRomHDTEgRcwCs5glHtzfyATRcZhR4ujF p0wgVZwC9hKzOmeBdQsLuEusbn7HDGKzCKhK/Ln+CMzmFbCU+LNiExOELShxcuYTFhCbWUBb 4unNp3D2soWvmSHOU5D4+XQZ1BVOEjeXr2OCqBGRmN3ZxjyBUXgWklGzkIyahWTULCQtCxhZ VjFKphYU56bnFhsWGOallusVJ+YWl+al6yXn525iBMeoluYOxu2rPugdYmTiYDzEKMHBrCTC ++fsqSQh3pTEyqrUovz4otKc1OJDjNIcLErivBe6TsYLCaQnlqRmp6YWpBbBZJk4OKUamIrS VikGp5rJfFz4r/+1tVLjQYY9MmvPWh21PF07o2/BKY/r7z4+mDd54s7DTpsuTC7/kPBJ1Tsn 3Xj6WoMNn9Me3k/+7vRg/vWSPNMjfJrGKy/a8/3RWvNLvuTi3LP5F+aK3bbYKrbwy4ee850u V48VvVh76/uGyQczc5qXldty6RV+y3l8vLD92PNL7KyOZ2cKiuTotzovfTmJ8/KKh2yiSvEh 3Je3as1iWrH3lZTx+s6HS1IsrRYdd4423fsj6id/T32v9lSWBS6nOeQy9/F3BHgZN3I8XjP/ iu6Ghe8uJ9WcFXKf8WS/a9SP65qqYu/SBDtXtQRx853tta2+ou4vbjrH2UVvXqfEnyePvI4o sRRnJBpqMRcVJwIAak46/0ADAAA= X-CMS-MailID: 20220712004443epcas2p4ed1e9ac5497517407000b08623556801 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: 20220629004356epcas2p408afcd3d19d926a86d98e887e25e93bc References: <20220629004141.51484-1-chanho61.park@samsung.com> <4fb8c922-08aa-2ee3-8073-95b8a26bf5db@samsung.com> Precedence: bulk List-ID: X-Mailing-List: linux-serial@vger.kernel.org > > + if (mctrl & TIOCM_LOOP) > > + ucon =7C=3D S3C2410_UCON_LOOPBACK; > > + else > > + ucon &=3D =7ES3C2410_UCON_LOOPBACK; > > + > > + wr_regl(port, S3C2410_UCON, ucon); >=20 > S3C2410_UCON must be modified at least under the local_irq_save() or port > lock, otherwise it breaks kernel console operation on older Exynos SoCs > (especially when DMA mode is used). >=20 > The above read-modify-write sequence should be replaced with the followin= g > pattern: >=20 > if (mctrl & TIOCM_LOOP) > s3c24xx_set_bit(port, S3C2410_UCON_LOOPBACK, S3C2410_UCO= N); > else > s3c24xx_clear_bit(port, S3C2410_UCON_LOOPBACK, S3C2410_U= CON); All the set_mctrl() call can be protected by spin_=5Bun=5Dlock_irq=5Bsave/r= estore=5D with port->lock. So, I think it is not required. Best Regards, Chanho Park