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[144.178.202.142]) by smtp.gmail.com with ESMTPSA id 4fb4d7f45d1cf-6a1e7cab26fsm604018a12.7.2026.08.07.07.30.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 07 Aug 2026 07:30:22 -0700 (PDT) Message-ID: <3554d8d1-65f7-4556-8b99-1c03e0cdca53@fairphone.com> Date: Fri, 7 Aug 2026 16:30:22 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH RFT 2/3] media: i2c: dw9719: Add DW9800W support To: Sakari Ailus , Danila Tikhonov , Luca Weiss Cc: Mauro Carvalho Chehab , Rob Herring , Krzysztof Kozlowski , Conor Dooley , =?UTF-8?Q?Andr=C3=A9_Apitzsch?= , Daniel Scally , Bjorn Andersson , Konrad Dybcio , Eugene Lepshy , Vasiliy Doylov , Achill Gilgenast , linux-media@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, ~postmarketos/upstreaming@lists.sr.ht References: <20260801-dw9800w-clean-v1-0-38978de67963@mainlining.org> <20260801-dw9800w-clean-v1-2-38978de67963@mainlining.org> Content-Language: en-US From: Griffin Kroah-Hartman In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hello Sakari, Danilla, On 05/08/2026 13:29, Sakari Ailus wrote: > Hi Danila, Griffin, > > On Tue, Aug 04, 2026 at 09:27:01PM +0300, Danila Tikhonov wrote: >> Hi Sakari, >> >> Thank you for your comment. >> >> On 04/08/2026 11:40, Sakari Ailus wrote: >>> Hi Danila, >>> >>> Thank you for the patch. >>> >>> On Sat, Aug 01, 2026 at 09:04:15PM +0300, Danila Tikhonov wrote: >>>> The DW9800W uses the same chip ID and register layout as the DW9800K, >>>> but requires different default VCM frequency value. >>> Is this a real difference between the two models or what fits for the >>> attached lens? Too bad the datasheet isn't publicly available. :-( >>> >>> At least the differing default and constraints for dongwoon,vcm-prescale >>> needs to be documented in bindings. >> I share your skepticism and have essentially the same concerns. Since I >> do not have the DW9800K datasheet, I cannot say with certainty how it >> differs from the DW9800W. > Indeed. The limits should have been added for dw9800k, too, but I guess I > missed this in review. :-\ > >> In particular, the parameter referred to as the VCM frequency in the >> driver is used to derive the SACT value. For the DW9800W, SACT[5:0] >> defines the actuator resonance period in SAC mode and the one-step >> period in LSC mode. The datasheet gives the corresponding formulas as: >> - tVIB = 6.3 ms + SACT * 0.1 ms >> - LSC 1-step period = 252 µs + SACT * 4 µs >> >> Therefore, the default value may differ between the DW9800K and DW9800W >> if the formulas or timing characteristics used to calculate SACT are >> different. > Griffin, would you be able to comment this? After checking on my side, DW9800W and K are almost identical in both structure and register values, including how tVIB and tLSC are calculated, DW9800K has an extra register that can change the output current to 130mA but we don't ever use that. We didn't have a datasheet when working on the DW9800k so we had to go off of the downstream driver during runtime to get our register values. The datasheet is a much more reliable source to be using for this instead. My colleague has already identified ways to fix the bindings, which we will tackle ourselves. > Another matter: the comment on dw9800k says there's no device ID. So is > there a device ID that wasn't just checked earlier or is there really no > device ID? Indeed, it turns out the DW9800K DOES have an info register, which should be 0xEB, that's on us for not updating it after we received more documentation. Thanks for drawing our attention to this! Nice patch. Griffin