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[2003:e4:1f16:2000:f22f:74ff:fe1f:3a53]) by smtp.gmail.com with ESMTPSA id 2adb3069b0e04-52b7d42911fsm222977e87.281.2024.05.30.06.18.37 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 30 May 2024 06:18:38 -0700 (PDT) Content-Type: multipart/signed; boundary=bcb7fe86b3b9e469b48e922bcd55856b7b09e063ce70f9d068a77cd6a2a0; micalg=pgp-sha256; protocol="application/pgp-signature" Precedence: bulk X-Mailing-List: linux-tegra@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Date: Thu, 30 May 2024 15:18:37 +0200 Message-Id: Cc: , Subject: Re: [PATCH V2] staging: nvec: make i2c controller register writes robust From: "Thierry Reding" To: "Marc Dietrich" , X-Mailer: aerc 0.16.0-1-0-g560d6168f0ed-dirty References: <20240526193932.57277-1-marvin24@gmx.de> In-Reply-To: <20240526193932.57277-1-marvin24@gmx.de> --bcb7fe86b3b9e469b48e922bcd55856b7b09e063ce70f9d068a77cd6a2a0 Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 On Sun May 26, 2024 at 9:39 PM CEST, Marc Dietrich wrote: > The i2c controller needs to read back the data written to its registers. > This way we can avoid the long delay in the interrupt handler. > > Signed-off-by: Marc Dietrich > --- > V2: rename i2c_writel to tegra_i2c_writel > drivers/staging/nvec/nvec.c | 41 ++++++++++++++++++++++--------------- > 1 file changed, 24 insertions(+), 17 deletions(-) Hi Marc, I've been trying to find out why we need to do these register read backs and so far I haven't found anything tangible. The only thing I was able to find that sounds like it could be remotely related to this is a mention of the interface clock being fixed at 72 MHz. So I'm wondering if you could perhaps verify in your setup what the I2C module clock is for the NVEC controller (any dump of the clk_summary debugfs file after boot would do). Since I'm not sure we'll get to the bottom of this, this looks clean and is certainly an improvement over the udelay(100), so: Reviewed-by: Thierry Reding --bcb7fe86b3b9e469b48e922bcd55856b7b09e063ce70f9d068a77cd6a2a0 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEiOrDCAFJzPfAjcif3SOs138+s6EFAmZYfK4ACgkQ3SOs138+ s6H7WhAAiSVAvfdQncK4PX/fpaBQU4TG0iL3ie0dSRJzUFJVyG4sqqP9JsiTBH5O EXPkht+5ol9LDgnB7oHh2k9jkTBZUNx5ZbQW93XdpbFNiPIuiGmf9IDbfa0fac00 Qx7Vk1yN/ET3ajqfYOjiyKaOLGZ2ohXnEMPo+xpT69m0f6kNA689cKSGLJBExznY msnvZysWOLi4KrQ5X99P4pHccR8uqSo3qT5VyT62jCztFDEZ2UWgekbdlIWD2VHE odtqSXc3bX+JwVRRcZPNqX7SAyRs0w7hJKZ5iwuGPJJQcgJM4eYs8X81Ye/XFTrj bvownMnPCA3l+vNonqAio/IrHXdLY7SBZBSCfvH1jRLhO4neXfc/C3jyvVXgfzpq T8eE5rZLLPeWRsWQZp2QhjDJV4vadGMh/NO/kv9afdxZ4TgyhqsLYqPRIQM0c+WJ oj2z9tIu5o4ZEA6nYbqKZo8RuqcvkTazmufPsL5T0zkn7fXcwQzTF6j2AeTFZgtX UEmKiBHysZFC1/LzRXbhSxYp2HzKECXc1C0JqteNcnnLGDywW2zbdw9zCxchDOVo mhND9qgQu6DigzUdxj8/Ht/ZUcmQokqFPKSTbPWrvEXVqtpFgvoMWakXqvnonfV2 UCRsENKvCuWSM6QR9Fo3KtKK/hIqSZPl5xeSZbXvv2YPjT8z7Hw= =rKEX -----END PGP SIGNATURE----- --bcb7fe86b3b9e469b48e922bcd55856b7b09e063ce70f9d068a77cd6a2a0--