From: Can Guo <can.guo@oss•qualcomm.com>
To: Krzysztof Kozlowski <krzk@kernel•org>
Cc: bvanassche@acm•org, beanhuo@micron•com, peter.wang@mediatek•com,
martin.petersen@oracle•com, mani@kernel•org,
linux-scsi@vger•kernel.org, Alim Akhtar <alim.akhtar@samsung•com>,
Avri Altman <avri.altman@wdc•com>, Rob Herring <robh@kernel•org>,
Krzysztof Kozlowski <krzk+dt@kernel•org>,
Conor Dooley <conor+dt@kernel•org>,
Matthias Brugger <matthias.bgg@gmail•com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora•com>,
Zhaoming Luo <zhml@posteo•com>,
Ram Kumar Dwivedi <quic_rdwivedi@quicinc•com>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger•kernel.org>,
open list <linux-kernel@vger•kernel.org>,
"moderated list:ARM/Mediatek SoC support:Keyword:mediatek"
<linux-arm-kernel@lists•infradead.org>,
"moderated list:ARM/Mediatek SoC support:Keyword:mediatek"
<linux-mediatek@lists•infradead.org>
Subject: Re: [PATCH v6 1/2] dt-bindings: ufs: Document static TX Equalization settings properties
Date: Sat, 30 May 2026 21:57:37 +0800 [thread overview]
Message-ID: <dff3c74f-0c46-4ac1-914a-9ea8bd40316c@oss.qualcomm.com> (raw)
In-Reply-To: <ada65ce2-6736-44fe-9396-d3ed632274ce@oss.qualcomm.com>
On 5/30/2026 8:45 PM, Can Guo wrote:
>
>
> On 5/30/2026 12:58 AM, Krzysztof Kozlowski wrote:
>> On Fri, May 29, 2026 at 04:33:37AM -0700, Can Guo wrote:
>>> UFS v5.0/UFSHCI v5.0 add HS-G6 support (46.6 Gbps/lane) via UniPro v3.0
>>> and M-PHY v6.0. In these specs, TX Equalization is defined for all High
>>> Speed Gears (not only HS-G6) to compensate channel loss and improve
>>> signal
>>> integrity at high speed operation.
>>>
>>> For HS-G6, M-PHY uses PAM4 1b1b line coding, Pre-Coding may also be
>>> required depending on channel characteristics.
>>>
>>> Add vendor-neutral DT properties:
>>>
>>> - patternProperties for txeq-preshoot-g[1-6] and txeq-deemphasis-g[1-6]
>>> - fixed property tx-precode-enable-g6
>>>
>>> Each property is a uint32 array of per-lane tuples:
>>> <Host_Lane0 Device_Lane0>, [<Host_Lane1 Device_Lane1>]
>>>
>>> Accept 2 or 4 values (x1/x2 lane configs). PreShoot and DeEmphasis
>>> values
>>> are 0..7. Precode enable values are 0/1 and only applicable to HS-G6.
>>>
>>> Acked-by: Manivannan Sadhasivam <mani@kernel•org>
>>> Reviewed-by: Bean Huo <beanhuo@micron•com>
>>> Reviewed-by: Peter Wang <peter.wang@mediatek•com>
>>> Signed-off-by: Can Guo <can.guo@oss•qualcomm.com>
>>> ---
>>> .../devicetree/bindings/ufs/ufs-common.yaml | 45
>>> +++++++++++++++++++
>>> 1 file changed, 45 insertions(+)
>>>
>>> diff --git a/Documentation/devicetree/bindings/ufs/ufs-common.yaml
>>> b/Documentation/devicetree/bindings/ufs/ufs-common.yaml
>>> index ed97f5682509..d90cf25adfa5 100644
>>> --- a/Documentation/devicetree/bindings/ufs/ufs-common.yaml
>>> +++ b/Documentation/devicetree/bindings/ufs/ufs-common.yaml
>>> @@ -105,6 +105,51 @@ properties:
>>> Restricts the UFS controller to rate-a or rate-b for both TX
>>> and
>>> RX directions.
>>> + tx-precode-enable-g6:
>>> + $ref: /schemas/types.yaml#/definitions/uint32-array
>>> + oneOf:
>>> + - minItems: 2
>>> + maxItems: 2
>>> + - minItems: 4
>>> + maxItems: 4
>>> + items:
>>> + enum: [0, 1]
>>> + description: |
>>> + Static TX Precode enable values for HS-G6 only.
>>> + Values are specified as per-lane tuples:
>>> + <Host_Lane0 Device_Lane0>, [<Host_Lane1 Device_Lane1>].
>> You need to include them in any of applicable examples, otherwise
>> nothing here is validated.
> Hi Krzysztof,
>
> Thanks for the review.
>
> Since no UFS5-capable SoC binding exists upstream yet (the target SoC is
> still pre-CS), there is no vendor-specific YAML to attach the example to.
>
> Is a synthetic example directly in ufs-common.yaml OK to you?
Let me update qcom,sm8650-ufshc.yaml as it includes sm8650 and others.
Thanks,
Can Guo.
>>
>> Why values cannot be on or off? Or even better: why you cannot just list
>> all the lanes which has it enabled, assuming disabled is by default?
> Thanks for the suggestions.
>
> For the "just list enabled lanes" suggestion: precode must be configured
> independently for the Host-side TX and Device-side TX transceivers within
> the same physical lane. A lane index list alone cannot capture this
> two-dimensional per-lane state. The tuple format <Host_LaneN
> Device_LaneN>
> is the minimal encoding that covers both.
>
> For the "on/off" suggestion: the on/off string pattern is used with
> single-value properties (e.g. LED default-state) read via
> of_property_read_string(). I am not aware of precedent for on/off as a
> string array for per-lane tuples.
>>
>>> +
>>> +patternProperties:
>>> + "^txeq-preshoot-g[1-6]$":
>>> + $ref: /schemas/types.yaml#/definitions/uint32-array
>>> + oneOf:
>>> + - minItems: 2
>>> + maxItems: 2
>>> + - minItems: 4
>>> + maxItems: 4
>>> + items:
>>> + minimum: 0
>>> + maximum: 7
>> What is the meaning of values? Nothing here refers to the spec, so is
>> this driver specific?
> These are not driver-specific. PreShoot and DeEmphasis are standard
> features of the MIPI M-PHY / UniPro stack. The range [0, 7] is defined
> in the UniPro specification for the relevant PA layer attributes, and
> each
> value maps to a specific dB level as defined in the M-PHY specification.
> I will add the value-to-dB mapping table to the property descriptions
> in v7.
>
> Thanks,
> Can Guo.
>>
>> Best regards,
>> Krzysztof
>>
>
next prev parent reply other threads:[~2026-05-30 13:58 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20260529113338.984301-1-can.guo@oss.qualcomm.com>
2026-05-29 11:33 ` [PATCH v6 1/2] dt-bindings: ufs: Document static TX Equalization settings properties Can Guo
2026-05-29 16:58 ` Krzysztof Kozlowski
2026-05-30 12:45 ` Can Guo
2026-05-30 13:57 ` Can Guo [this message]
2026-05-30 17:33 ` Krzysztof Kozlowski
2026-05-31 1:41 ` Can Guo
2026-05-31 4:48 ` Can Guo
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