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Wed, 30 Sep 2020 10:34:25 +0000 (UTC) Subject: Re: mcp25xxfd driver questions To: =?UTF-8?Q?Magnus_Aagaard_S=c3=b8rensen?= Cc: linux-can@vger.kernel.org, Bas Vermeulen , Thomas Kopp References: <66662c88-aa9a-325d-8152-c5befbfafa2a@pengutronix.de> <1ee0af54-cdd6-4dc7-1956-e302bec716ff@csselectronics.com> <6bfc53ae-e40c-98b1-af78-66aca4d911cc@pengutronix.de> From: Marc Kleine-Budde Autocrypt: addr=mkl@pengutronix.de; prefer-encrypt=mutual; keydata= mQINBFFVq30BEACtnSvtXHoeHJxG6nRULcvlkW6RuNwHKmrqoksispp43X8+nwqIFYgb8UaX zu8T6kZP2wEIpM9RjEL3jdBjZNCsjSS6x1qzpc2+2ivjdiJsqeaagIgvy2JWy7vUa4/PyGfx QyUeXOxdj59DvLwAx8I6hOgeHx2X/ntKAMUxwawYfPZpP3gwTNKc27dJWSomOLgp+gbmOmgc 6U5KwhAxPTEb3CsT5RicsC+uQQFumdl5I6XS+pbeXZndXwnj5t84M+HEj7RN6bUfV2WZO/AB Xt5+qFkC/AVUcj/dcHvZwQJlGeZxoi4veCoOT2MYqfR0ax1MmN+LVRvKm29oSyD4Ts/97cbs XsZDRxnEG3z/7Winiv0ZanclA7v7CQwrzsbpCv+oj+zokGuKasofzKdpywkjAfSE1zTyF+8K nxBAmzwEqeQ3iKqBc3AcCseqSPX53mPqmwvNVS2GqBpnOfY7Mxr1AEmxdEcRYbhG6Xdn+ACq Dq0Db3A++3PhMSaOu125uIAIwMXRJIzCXYSqXo8NIeo9tobk0C/9w3fUfMTrBDtSviLHqlp8 eQEP8+TDSmRP/CwmFHv36jd+XGmBHzW5I7qw0OORRwNFYBeEuiOIgxAfjjbLGHh9SRwEqXAL kw+WVTwh0MN1k7I9/CDVlGvc3yIKS0sA+wudYiselXzgLuP5cQARAQABtCZNYXJjIEtsZWlu ZS1CdWRkZSA8bWtsQHBlbmd1dHJvbml4LmRlPokCVAQTAQoAPgIbAwIeAQIXgAULCQgHAwUV CgkICwUWAgMBABYhBMFAC6CzmJ5vvH1bXCte4hHFiupUBQJfEWX4BQkQo2czAAoJECte4hHF iupUvfMP/iNtiysSr5yU4tbMBzRkGov1/FjurfH1kPweLVHDwiQJOGBz9HgM5+n8boduRv36 0lU32g3PehN0UHZdHWhygUd6J09YUi2mJo1l2Fz1fQ8elUGUOXpT/xoxNQjslZjJGItCjza8 +D1DO+0cNFgElcNPa7DFBnglatOCZRiMjo4Wx0i8njEVRU+4ySRU7rCI36KPts+uVmZAMD7V 3qiR1buYklJaPCJsnXURXYsilBIE9mZRmQjTDVqjLWAit++flqUVmDjaD/pj2AQe2Jcmd2gm sYW5P1moz7ACA1GzMjLDmeFtpJOIB7lnDX0F/vvsG3V713/701aOzrXqBcEZ0E4aWeZJzaXw n1zVIrl/F3RKrWDhMKTkjYy7HA8hQ9SJApFXsgP334Vo0ea82H3dOU755P89+Eoj0y44MbQX 7xUy4UTRAFydPl4pJskveHfg4dO6Yf0PGIvVWOY1K04T1C5dpnHAEMvVNBrfTA8qcahRN82V /iIGB+KSC2xR79q1kv1oYn0GOnWkvZmMhqGLhxIqHYitwH4Jn5uRfanKYWBk12LicsjRiTyW Z9cJf2RgAtQgvMPvmaOL8vB3U4ava48qsRdgxhXMagU618EszVdYRNxGLCqsKVYIDySTrVzu ZGs2ibcRhN4TiSZjztWBAe1MaaGk05Ce4h5IdDLbOOxhuQENBF8SDLABCADohJLQ5yffd8Sq 8Lo9ymzgaLcWboyZ46pY4CCCcAFDRh++QNOJ8l4mEJMNdEa/yrW4lDQDhBWV75VdBuapYoal LFrSzDzrqlHGG4Rt4/XOqMo6eSeSLipYBu4Xhg59S9wZOWbHVT/6vZNmiTa3d40+gBg68dQ8 iqWSU5NhBJCJeLYdG6xxeUEtsq/25N1erxmhs/9TD0sIeX36rFgWldMwKmZPe8pgZEv39Sdd B+ykOlRuHag+ySJxwovfdVoWT0o0LrGlHzAYo6/ZSi/Iraa9R/7A1isWOBhw087BMNkRYx36 B77E4KbyBPx9h3wVyD/R6T0Q3ZNPu6SQLnsWojMzABEBAAGJAjwEGAEKACYWIQTBQAugs5ie b7x9W1wrXuIRxYrqVAUCXxIMsAIbDAUJAucGAAAKCRArXuIRxYrqVOu0D/48xSLyVZ5NN2Bb yqo3zxdv/PMGJSzM3JqSv7hnMZPQGy9XJaTc5Iz/hyXaNRwpH5X0UNKqhQhlztChuAKZ7iu+ 2VKzq4JJe9qmydRUwylluc4HmGwlIrDNvE0N66pRvC3h8tOVIsippAQlt5ciH74bJYXr0PYw Aksw1jugRxMbNRzgGECg4O6EBNaHwDzsVPX1tDj0d9t/7ClzJUy20gg8r9Wm/I/0rcNkQOpV RJLDtSbGSusKxor2XYmVtHGauag4YO6Vdq+2RjArB3oNLgSOGlYVpeqlut+YYHjWpaX/cTf8 /BHtIQuSAEu/WnycpM3Z9aaLocYhbp5lQKL6/bcWQ3udd0RfFR/Gv7eR7rn3evfqNTtQdo4/ YNmd7P8TS7ALQV/5bNRe+ROLquoAZvhaaa6SOvArcmFccnPeyluX8+o9K3BCdXPwONhsrxGO wrPI+7XKMlwWI3O076NqNshh6mm8NIC0mDUr7zBUITa67P3Q2VoPoiPkCL9RtsXdQx5BI9iI h/6QlzDxcBdw2TVWyGkVTCdeCBpuRndOMVmfjSWdCXXJCLXO6sYeculJyPkuNvumxgwUiK/H AqqdUfy1HqtzP2FVhG5Ce0TeMJepagR2CHPXNg88Xw3PDjzdo+zNpqPHOZVKpLUkCvRv1p1q m1qwQVWtAwMML/cuPga78rkBDQRfEXGWAQgAt0Cq8SRiLhWyTqkf16Zv/GLkUgN95RO5ntYM fnc2Tr3UlRq2Cqt+TAvB928lN3WHBZx6DkuxRM/Y/iSyMuhzL5FfhsICuyiBs5f3QG70eZx+ Bdj4I7LpnIAzmBdNWxMHpt0m7UnkNVofA0yH6rcpCsPrdPRJNOLFI6ZqXDQk9VF+AB4HVAJY BDU3NAHoyVGdMlcxev0+gEXfBQswEcysAyvzcPVTAqmrDsupnIB2f0SDMROQCLO6F+/cLG4L Stbz+S6YFjESyXblhLckTiPURvDLTywyTOxJ7Mafz6ZCene9uEOqyd/h81nZOvRd1HrXjiTE 1CBw+Dbvbch1ZwGOTQARAQABiQNyBBgBCgAmFiEEwUALoLOYnm+8fVtcK17iEcWK6lQFAl8R cZYCGwIFCQLnoRoBQAkQK17iEcWK6lTAdCAEGQEKAB0WIQQreQhYm33JNgw/d6GpyVqK+u3v qQUCXxFxlgAKCRCpyVqK+u3vqatQCAC3QIk2Y0g/07xNLJwhWcD7JhIqfe7Qc5Vz9kf8ZpWr +6w4xwRfjUSmrXz3s6e/vrQsfdxjVMDFOkyG8c6DWJo0TVm6Ucrf9G06fsjjE/6cbE/gpBkk /hOVz/a7UIELT+HUf0zxhhu+C9hTSl8Nb0bwtm6JuoY5AW0LP2KoQ6LHXF9KNeiJZrSzG6WE h7nf3KRFS8cPKe+trbujXZRb36iIYUfXKiUqv5xamhohy1hw+7Sy8nLmw8rZPa40bDxX0/Gi 98eVyT4/vi+nUy1gF1jXgNBSkbTpbVwNuldBsGJsMEa8lXnYuLzn9frLdtufUjjCymdcV/iT sFKziU9AX7TLZ5AP/i1QMP9OlShRqERH34ufA8zTukNSBPIBfmSGUe6G2KEWjzzNPPgcPSZx Do4jfQ/m/CiiibM6YCa51Io72oq43vMeBwG9/vLdyev47bhSfMLTpxdlDJ7oXU9e8J61iAF7 vBwerBZL94I3QuPLAHptgG8zPGVzNKoAzxjlaxI1MfqAD9XUM80MYBVjunIQlkU/AubdvmMY X7hY1oMkTkC5hZNHLgIsDvWUG0g3sACfqF6gtMHY2lhQ0RxgxAEx+ULrk/svF6XGDe6iveyc z5Mg5SUggw3rMotqgjMHHRtB3nct6XqgPXVDGYR7nAkXitG+nyG5zWhbhRDglVZ0mLlW9hij z3Emwa94FaDhN2+1VqLFNZXhLwrNC5mlA6LUjCwOL+zb9a07HyjekLyVAdA6bZJ5BkSXJ1CO 5YeYolFjr4YU7GXcSVfUR6fpxrb8N+yH+kJhY3LmS9vb2IXxneE/ESkXM6a2YAZWfW8sgwTm 0yCEJ41rW/p3UpTV9wwE2VbGD1XjzVKl8SuAUfjjcGGys3yk5XQ5cccWTCwsVdo2uAcY1MVM HhN6YJjnMqbFoHQq0H+2YenTlTBn2Wsp8TIytE1GL6EbaPWbMh3VLRcihlMj28OUWGSERxat xlygDG5cBiY3snN3xJyBroh5xk/sHRgOdHpmujnFyu77y4RTZ2W8 Message-ID: Date: Wed, 30 Sep 2020 12:34:21 +0200 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: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="31zMAz8kZZ87vizRkzwv19FFCrtEq7dDc" X-SA-Exim-Connect-IP: 2001:67c:670:201:5054:ff:fe8d:eefb X-SA-Exim-Mail-From: mkl@pengutronix.de X-SA-Exim-Scanned: No (on metis.ext.pengutronix.de); SAEximRunCond expanded to false X-PTX-Original-Recipient: linux-can@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-can@vger.kernel.org This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --31zMAz8kZZ87vizRkzwv19FFCrtEq7dDc Content-Type: multipart/mixed; boundary="wfdRpZ8GL1xmmX6lg1Z42LbbRjdrHQQkK"; protected-headers="v1" From: Marc Kleine-Budde To: =?UTF-8?Q?Magnus_Aagaard_S=c3=b8rensen?= Cc: linux-can@vger.kernel.org, Bas Vermeulen , Thomas Kopp Message-ID: Subject: Re: mcp25xxfd driver questions References: <66662c88-aa9a-325d-8152-c5befbfafa2a@pengutronix.de> <1ee0af54-cdd6-4dc7-1956-e302bec716ff@csselectronics.com> <6bfc53ae-e40c-98b1-af78-66aca4d911cc@pengutronix.de> In-Reply-To: --wfdRpZ8GL1xmmX6lg1Z42LbbRjdrHQQkK Content-Type: text/plain; charset=utf-8 Content-Language: de-DE Content-Transfer-Encoding: quoted-printable On 9/30/20 12:11 PM, Magnus Aagaard S=C3=B8rensen wrote: >> Ah, ok. More users are always welcome. Which SoC are you using? > We are controlling the test boards using a Raspberry Pi 4, so I assume = > it is a Broadcom BCM2711. Ok....The SPI clock situation on the rpi4 is not optimal. But's a a diffe= rent story :) >>>>> 1. I could not find any references to the GPIOs of the chip. Is it >>>>> correct that these are not exposed to the host system? >>>> ACK, gpio support is not implemented yet. Drop me a note, if you nee= d it. >>> On the board I'm currently working on getting up and running, we have= no >>> need for GPIOs or any of the other advanced features of the MCP2518FD= =2E >>> On our older board, we do utilize the GPIO and oscillator output >>> functionality of the chip. It works for now with the old driver, so i= t >>> is not a priority. It would be nice to have this functionality in the= >>> future for us. >> Bas Vermeulen (Cc'ed) is using the mainline driver (or an older versio= n of it) >> and send a pull request for oscillator output >> (https://github.com/marckleinebudde/linux/pull/5). I did an initial re= view >> there. This is a good starting point if you want to contribute (or dro= p me a >> note for commercial support). >> >>>>> 2. When setting the oscillator frequency outside the >>>>> MCP25XXFD_SYSCLOCK_HZ_MIN and MCP25XXFD_SYSCLOCK_HZ_MAX range, the >>>>> frequency is compared to the max value scaled by the max PLL value.= Is >>>>> the intention to compare with the min value? Currently, an external= >>>>> oscillator of 4 MHz and a PLL value of 10, resulting in 40 MHz, is >>>>> treated as being too low. >>>> This is intended. I have no hardware with a 4MHz osc to test, so I d= ecided to >>>> not support the 4MHz osc for now. If you design new hardware I sugge= st to use a >>>> 40MHz osc, as probably no one has tested the hardware thoroughly in = the PLL >>>> mode. If you need 4MHz support, it can be added, given there is hard= ware. >>> I can provide some test information if needed, as I have internal >>> testing hardware with a 4 MHz oscillator already. Are there any speci= fic >>> message sequences that needs to be tested? >> You have to take care of the PLL in the functions mcp25xxfd_chip_clock= _enable(), >> mcp25xxfd_chip_softreset_check(), mcp25xxfd_chip_clock_init(). >> >> The MCP25XXFD_REG_OSC_PLLEN bit has to be set and the MCP25XXFD_REG_OS= C_PLLRDY >> bit has to be polled. >> >> I'm not sure what SPI speed you can use, when communicating with the m= cp, if the >> PLL is not enabled. Maybe Thomas (Cc'ed) can answer this. I suspect yo= u can only >> use 2MHZ (or rather 85% of it) if you have a 4 MHz OSC with PLL still = disabled. > Thanks for the hints, I'll see if I can adapt it to our use case. I'm looking forward for patches :) Marc --=20 Pengutronix e.K. | Marc Kleine-Budde | Embedded Linux | https://www.pengutronix.de | Vertretung West/Dortmund | Phone: +49-231-2826-924 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | --wfdRpZ8GL1xmmX6lg1Z42LbbRjdrHQQkK-- --31zMAz8kZZ87vizRkzwv19FFCrtEq7dDc Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQEzBAEBCgAdFiEEK3kIWJt9yTYMP3ehqclaivrt76kFAl90Xy4ACgkQqclaivrt 76nsgwf/XbZhfAUuA7gkUO8igvvIKYP5UyUJRfGbYS+7ltjRqOXEiOnqxssNq4u9 gXliRV5wqP6xFU7oNVdcqArX90p6aQOhsTOAzIKisMQX5bE4QlhW309Ph+o7jiui Nfe4RA7aJL43vM7L560TSZ44iFvm0M10pms+Xds0+Ckc8DuVCbbmA57jvRrDEbQS mb/owzqVFUA6PtYk/6YCAD2tCofMfVWp714y08G9kV0Hr+AWQHSsEMRkkA6tmeCp xay2JWJKP0ZI3bGznRL16lK5BIiTxKpips9wwQkE9FxWf0Eqhf+IbxqnJ+uHOVLF wQpgZYuGCwPd1uYmP0dqvyMj3qcBIw== =BuRN -----END PGP SIGNATURE----- --31zMAz8kZZ87vizRkzwv19FFCrtEq7dDc--