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: Sun, 31 May 2026 12:48:29 +0800 [thread overview]
Message-ID: <64bd6272-6111-4ffa-8a4a-366d0c287693@oss.qualcomm.com> (raw)
In-Reply-To: <7d49742a-7602-4f58-8dce-7e02664b783c@oss.qualcomm.com>
On 5/31/2026 9:41 AM, Can Guo wrote:
>
>
> On 5/31/2026 1:33 AM, Krzysztof Kozlowski wrote:
>> On 30/05/2026 14:45, 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
>> I would imagine cover letter or commit msg would briefly mention that.
> Thanks for the clarification. Will do.
>>
>>> 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?
>> Skip example in such case.
>>
>>>> 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.
>> Again, why do you need to encode '0'?
> The tuple is still needed because Precoding is configured per
> transmitter-receiver pair,
> so each lane has two independent states:
> - Host_TX -> Device_RX
> - Device_TX -> Host_RX
> A lane-only enabled list cannot represent directional combinations
> like lane0 =
> (on, off) vs (off, on).
How about we split into two properties, something like below?
tx-precode-enable-g6-host-lanes = <0 1>
tx-precode-enable-g6-device-lanes = <1>
Only listed lanes are enabled; unlisted lanes are disabled by default.
Are you OK with this approach?
Thanks,
Can Guo.
>>
>>> 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.
>> git grep string-array. Plenty of precedents.
> I will keep the per-lane tuple model but switch tx-precode-enable-g6
> from 0/1 to
> "on"/"off" (string array) in v7.
>
> Thanks,
> Can Guo.
>>
>> Best regards,
>> Krzysztof
>
prev parent reply other threads:[~2026-05-31 4:48 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
2026-05-30 17:33 ` Krzysztof Kozlowski
2026-05-31 1:41 ` Can Guo
2026-05-31 4:48 ` Can Guo [this message]
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