Re: [PATCH v4 12/23] ata: libahci: Extend port-cmd flags set with port capabilities

Damien Le Moal
2022-06-16T00:28:47Z

On 2022/06/16 5:58, Serge Semin wrote:
> On Tue, Jun 14, 2022 at 05:32:41PM +0900, Damien Le Moal wrote:
>> On 6/10/22 17:17, Serge Semin wrote:
>>> Currently not all of the Port-specific capabilities listed in the
>>
>> s/listed/are listed
>>
>>> PORT_CMD-enumeration. Let's extend that set with the Cold Presence
>>> Detection and Mechanical Presence Switch attached to the Port flags [1] so
>>> to closeup the set of the platform-specific port-capabilities flags. Note
>>> these flags are supposed to be set by the platform firmware if there is
>>> one. Alternatively as we are about to do they can be set by means of the
>>> OF properties.
>>>
>>> While at it replace PORT_IRQ_DEV_ILCK with PORT_IRQ_DMPS and fix the
>>> comment there. In accordance with [2] that IRQ flag is supposed to
>>> indicate the state of the signal coming from the Mechanical Presence
>>> Switch.
>>>
>>> [1] Serial ATA AHCI 1.3.1 Specification, p.27
>>> [2] Serial ATA AHCI 1.3.1 Specification, p.24, p.88
>>>
>>> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
>>> Reviewed-by: Hannes Reinecke <hare@suse.de>
>>>
>>> ---
>>>
>>> Changelog v4:
>>> - Fix the DMPS macros name in the patch log. (@Sergei Shtylyov)
>>> ---
>>> drivers/ata/ahci.h | 7 ++++++-
>>> 1 file changed, 6 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/ata/ahci.h b/drivers/ata/ahci.h
>>> index 7d834deefeb9..f501531bd1b3 100644
>>> --- a/drivers/ata/ahci.h
>>> +++ b/drivers/ata/ahci.h
>>> @@ -138,7 +138,7 @@ enum {
>>> PORT_IRQ_BAD_PMP = (1 << 23), /* incorrect port multiplier */
>>>
>>> PORT_IRQ_PHYRDY = (1 << 22), /* PhyRdy changed */
>>> - PORT_IRQ_DEV_ILCK = (1 << 7), /* device interlock */
>>> + PORT_IRQ_DMPS = (1 << 7), /* mechanical presence status */
>>> PORT_IRQ_CONNECT = (1 << 6), /* port connect change status */
>>> PORT_IRQ_SG_DONE = (1 << 5), /* descriptor processed */
>>> PORT_IRQ_UNK_FIS = (1 << 4), /* unknown FIS rx'd */
>>> @@ -166,6 +166,8 @@ enum {
>>> PORT_CMD_ATAPI = (1 << 24), /* Device is ATAPI */
>>> PORT_CMD_FBSCP = (1 << 22), /* FBS Capable Port */
>>> PORT_CMD_ESP = (1 << 21), /* External Sata Port */
>>> + PORT_CMD_CPD = (1 << 20), /* Cold Presence Detection */
>>> + PORT_CMD_MPSP = (1 << 19), /* Mechanical Presence Switch */
>>> PORT_CMD_HPCP = (1 << 18), /* HotPlug Capable Port */
>>> PORT_CMD_PMP = (1 << 17), /* PMP attached */
>>> PORT_CMD_LIST_ON = (1 << 15), /* cmd list DMA engine running */
>>> @@ -181,6 +183,9 @@ enum {
>>> PORT_CMD_ICC_PARTIAL = (0x2 << 28), /* Put i/f in partial state */
>>> PORT_CMD_ICC_SLUMBER = (0x6 << 28), /* Put i/f in slumber state */
>>>
>>> + PORT_CMD_CAP = PORT_CMD_HPCP | PORT_CMD_MPSP |
>>> + PORT_CMD_CPD | PORT_CMD_ESP | PORT_CMD_FBSCP,
>>
>
>> What is this one for ? A comment above it would be nice.
>
> Isn't it obviously inferrable from the definition and the item name?

I am guessing from the name. Am I guessing OK ? A comment would still be nice.
Why just these bits ? There are more cap/support indicator bits in that port cmd
bitfield. So why this particular set of bits ? What do they mean all together ?

Sure I can go and read the specs to figure it out. But again, a comment would
avoid readers of the code to have to decrypt all that.

>
> -Sergey
>
>>
>>> +
>>> /* PORT_FBS bits */
>>> PORT_FBS_DWE_OFFSET = 16, /* FBS device with error offset */
>>> PORT_FBS_ADO_OFFSET = 12, /* FBS active dev optimization offset */
>>
>>
>> --
>> Damien Le Moal
>> Western Digital Research

--
Damien Le Moal
Western Digital Research