Received-SPF: pass (google.com: domain of linux-kernel+bounces-60016-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Message-ID: <8a7b63a8-0583-43cf-9876-8a964c8b77ee@linaro.org>
Date: Fri, 9 Feb 2024 22:14:25 +0100
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v6 5/6] arm64: dts: qcom: sm8450: Add opp table support to
 PCIe
Content-Language: en-US
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Manivannan Sadhasivam <mani@kernel.org>,
 Krishna chaitanya chundru <quic_krichai@quicinc.com>,
 Bjorn Andersson <andersson@kernel.org>, Bjorn Helgaas <bhelgaas@google.com>,
 Lorenzo Pieralisi <lpieralisi@kernel.org>,
 =?UTF-8?Q?Krzysztof_Wilczy=C5=84ski?= <kw@linux.com>,
 Rob Herring <robh@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>, Rob Herring <robh+dt@kernel.org>,
 Johan Hovold <johan+linaro@kernel.org>, Brian Masney <bmasney@redhat.com>,
 Georgi Djakov <djakov@kernel.org>, linux-arm-msm@vger.kernel.org,
 vireshk@kernel.org, quic_vbadigan@quicinc.com, quic_skananth@quicinc.com,
 quic_nitegupt@quicinc.com, linux-pci@vger.kernel.org,
 devicetree@vger.kernel.org, linux-kernel@vger.kernel.org
References: <20240112-opp_support-v6-5-77bbf7d0cc37@quicinc.com>
 <20240129160420.GA27739@thinkpad>
 <20240130061111.eeo2fzaltpbh35sj@vireshk-i7>
 <20240130071449.GG32821@thinkpad>
 <20240130083619.lqbj47fl7aa5j3k5@vireshk-i7>
 <20240130094804.GD83288@thinkpad>
 <20240130095508.zgufudflizrpxqhy@vireshk-i7> <20240130131625.GA2554@thinkpad>
 <20240131052335.6nqpmccgr64voque@vireshk-i7>
 <610d5d7c-ec8d-42f1-81a2-1376b8a1a43f@linaro.org>
 <20240202073334.mkabgezwxn3qe7iy@vireshk-i7>
From: Konrad Dybcio <konrad.dybcio@linaro.org>
Autocrypt: addr=konrad.dybcio@linaro.org; keydata=
 xsFNBF9ALYUBEADWAhxdTBWrwAgDQQzc1O/bJ5O7b6cXYxwbBd9xKP7MICh5YA0DcCjJSOum
 BB/OmIWU6X+LZW6P88ZmHe+KeyABLMP5s1tJNK1j4ntT7mECcWZDzafPWF4F6m4WJOG27kTJ
 HGWdmtO+RvadOVi6CoUDqALsmfS3MUG5Pj2Ne9+0jRg4hEnB92AyF9rW2G3qisFcwPgvatt7
 TXD5E38mLyOPOUyXNj9XpDbt1hNwKQfiidmPh5e7VNAWRnW1iCMMoKqzM1Anzq7e5Afyeifz
 zRcQPLaqrPjnKqZGL2BKQSZDh6NkI5ZLRhhHQf61fkWcUpTp1oDC6jWVfT7hwRVIQLrrNj9G
 MpPzrlN4YuAqKeIer1FMt8cq64ifgTzxHzXsMcUdclzq2LTk2RXaPl6Jg/IXWqUClJHbamSk
 t1bfif3SnmhA6TiNvEpDKPiT3IDs42THU6ygslrBxyROQPWLI9IL1y8S6RtEh8H+NZQWZNzm
 UQ3imZirlPjxZtvz1BtnnBWS06e7x/UEAguj7VHCuymVgpl2Za17d1jj81YN5Rp5L9GXxkV1
 aUEwONM3eCI3qcYm5JNc5X+JthZOWsbIPSC1Rhxz3JmWIwP1udr5E3oNRe9u2LIEq+wH/toH
 kpPDhTeMkvt4KfE5m5ercid9+ZXAqoaYLUL4HCEw+HW0DXcKDwARAQABzShLb25yYWQgRHli
 Y2lvIDxrb25yYWQuZHliY2lvQGxpbmFyby5vcmc+wsGOBBMBCAA4FiEEU24if9oCL2zdAAQV
 R4cBcg5dfFgFAmQ5bqwCGwMFCwkIBwIGFQoJCAsCBBYCAwECHgECF4AACgkQR4cBcg5dfFjO
 BQ//YQV6fkbqQCceYebGg6TiisWCy8LG77zV7DB0VMIWJv7Km7Sz0QQrHQVzhEr3trNenZrf
 yy+o2tQOF2biICzbLM8oyQPY8B///KJTWI2khoB8IJSJq3kNG68NjPg2vkP6CMltC/X3ohAo
 xL2UgwN5vj74QnlNneOjc0vGbtA7zURNhTz5P/YuTudCqcAbxJkbqZM4WymjQhe0XgwHLkiH
 5LHSZ31MRKp/+4Kqs4DTXMctc7vFhtUdmatAExDKw8oEz5NbskKbW+qHjW1XUcUIrxRr667V
 GWH6MkVceT9ZBrtLoSzMLYaQXvi3sSAup0qiJiBYszc/VOu3RbIpNLRcXN3KYuxdQAptacTE
 mA+5+4Y4DfC3rUSun+hWLDeac9z9jjHm5rE998OqZnOU9aztbd6zQG5VL6EKgsVXAZD4D3RP
 x1NaAjdA3MD06eyvbOWiA5NSzIcC8UIQvgx09xm7dThCuQYJR4Yxjd+9JPJHI6apzNZpDGvQ
 BBZzvwxV6L1CojUEpnilmMG1ZOTstktWpNzw3G2Gis0XihDUef0MWVsQYJAl0wfiv/0By+XK
 mm2zRR+l/dnzxnlbgJ5pO0imC2w0TVxLkAp0eo0LHw619finad2u6UPQAkZ4oj++iIGrJkt5
 Lkn2XgB+IW8ESflz6nDY3b5KQRF8Z6XLP0+IEdLOOARkOW7yEgorBgEEAZdVAQUBAQdAwmUx
 xrbSCx2ksDxz7rFFGX1KmTkdRtcgC6F3NfuNYkYDAQgHwsF2BBgBCAAgFiEEU24if9oCL2zd
 AAQVR4cBcg5dfFgFAmQ5bvICGwwACgkQR4cBcg5dfFju1Q//Xta1ShwL0MLSC1KL1lXGXeRM
 8arzfyiB5wJ9tb9U/nZvhhdfilEDLe0jKJY0RJErbdRHsalwQCrtq/1ewQpMpsRxXzAjgfRN
 jc4tgxRWmI+aVTzSRpywNahzZBT695hMz81cVZJoZzaV0KaMTlSnBkrviPz1nIGHYCHJxF9r
 cIu0GSIyUjZ/7xslxdvjpLth16H27JCWDzDqIQMtg61063gNyEyWgt1qRSaK14JIH/DoYRfn
 jfFQSC8bffFjat7BQGFz4ZpRavkMUFuDirn5Tf28oc5ebe2cIHp4/kajTx/7JOxWZ80U70mA
 cBgEeYSrYYnX+UJsSxpzLc/0sT1eRJDEhI4XIQM4ClIzpsCIN5HnVF76UQXh3a9zpwh3dk8i
 bhN/URmCOTH+LHNJYN/MxY8wuukq877DWB7k86pBs5IDLAXmW8v3gIDWyIcgYqb2v8QO2Mqx
 YMqL7UZxVLul4/JbllsQB8F/fNI8AfttmAQL9cwo6C8yDTXKdho920W4WUR9k8NT/OBqWSyk
 bGqMHex48FVZhexNPYOd58EY9/7mL5u0sJmo+jTeb4JBgIbFPJCFyng4HwbniWgQJZ1WqaUC
 nas9J77uICis2WH7N8Bs9jy0wQYezNzqS+FxoNXmDQg2jetX8en4bO2Di7Pmx0jXA4TOb9TM
 izWDgYvmBE8=
In-Reply-To: <20240202073334.mkabgezwxn3qe7iy@vireshk-i7>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit

On 2.02.2024 08:33, Viresh Kumar wrote:
> On 01-02-24, 15:45, Konrad Dybcio wrote:
>> I'm lukewarm on this.
>>
>> A *lot* of hardware has more complex requirements than "x MBps at y MHz",
>> especially when performance counters come into the picture for dynamic
>> bw management.
>>
>> OPP tables can't really handle this properly.
> 
> There was a similar concern for voltages earlier on and we added the capability
> of adjusting the voltage for OPPs in the OPP core. Maybe something similar can
> be done here ?
> 
I really don't think it's fitting.. At any moment the device may require any
bandwidth value between 0 and MAX_BW_PER_LINK_GEN * LINK_WIDTH..

Konrad