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Date: Fri, 15 Apr 2016 10:18:58 +0800
From: "Li, Aubrey" <aubrey.li@...ux.intel.com>
To: Darren Hart <dvhart@...radead.org>
Cc: Andy Shevchenko <andy.shevchenko@...il.com>, qipeng.zha@...el.com,
platform-driver-x86@...r.kernel.org,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] platform:x86 decouple telemetry driver from the optional
IPC resources
On 2016/4/15 8:32, Darren Hart wrote:
> On Sun, Apr 10, 2016 at 09:46:48PM +0800, Li, Aubrey wrote:
>> On 2016/4/10 21:17, Andy Shevchenko wrote:
>>> On Thu, Mar 31, 2016 at 10:28 PM, Aubrey Li <aubrey.li@...ux.intel.com> wrote:
>>>> Currently the optional IPC resources prevent telemetry driver from
>>>> probing if these resources are not in ACPI table. This patch decouples
>>>> telemetry driver from these optional resources, so that telemetry driver
>>>> has dependency only on the necessary ACPI resources.
>>>
>>> Darren, I have comments as well.
>>>
>>>>
>>>> Signed-off-by: Aubrey Li <aubrey.li@...ux.intel.com>
>>>> ---
>>>> drivers/platform/x86/intel_pmc_ipc.c | 48 +++++++++++++++-----------------
>>>> drivers/platform/x86/intel_punit_ipc.c | 48 +++++++++++++++++++++-----------
>>>> 2 files changed, 54 insertions(+), 42 deletions(-)
>>>>
>>>> diff --git a/drivers/platform/x86/intel_pmc_ipc.c b/drivers/platform/x86/intel_pmc_ipc.c
>>>> index 092519e..29d9c02 100644
>>>> --- a/drivers/platform/x86/intel_pmc_ipc.c
>>>> +++ b/drivers/platform/x86/intel_pmc_ipc.c
>>>> @@ -686,8 +686,8 @@ static int ipc_plat_get_res(struct platform_device *pdev)
>>>> ipcdev.acpi_io_size = size;
>>>> dev_info(&pdev->dev, "io res: %pR\n", res);
>>>>
>>>> - /* This is index 0 to cover BIOS data register */
>>>> punit_res = punit_res_array;
>>>> + /* This is index 0 to cover BIOS data register */
>>>> res = platform_get_resource(pdev, IORESOURCE_MEM,
>>>> PLAT_RESOURCE_BIOS_DATA_INDEX);
>>>> if (!res) {
>>>> @@ -697,55 +697,51 @@ static int ipc_plat_get_res(struct platform_device *pdev)
>>>> *punit_res = *res;
>>>> dev_info(&pdev->dev, "punit BIOS data res: %pR\n", res);
>>>>
>>>> + /* This is index 1 to cover BIOS interface register */
>>>> res = platform_get_resource(pdev, IORESOURCE_MEM,
>>>> PLAT_RESOURCE_BIOS_IFACE_INDEX);
>>>> if (!res) {
>>>> dev_err(&pdev->dev, "Failed to get res of punit BIOS iface\n");
>>>> return -ENXIO;
>>>> }
>>>> - /* This is index 1 to cover BIOS interface register */
>>>> *++punit_res = *res;
>>>> dev_info(&pdev->dev, "punit BIOS interface res: %pR\n", res);
>>>>
>>>> + /* This is index 2 to cover ISP data register, optional */
>>>
>>> All above looks like a commentary fixes (except an additional
>>> 'optional' word in one case). Can you do this separately?
>>
>> I don't think it's necessary.
>>
>
> This is typically necessary as you would not want the comment fixes above to be
> backed out if the functional changes below were found to be buggy and reverted.
> This is why we encourage small functional changes. It protects against
> inadvertent reverts and facilitates review.
>
> That said, these comment changes continue below in a way that makes it a bit
> difficult to isolate them out, so I do not particularly object.
Yes, these comment changes are supposed to be together with the
functional changes, without functional changes, I won't touch these
comments.
>
> That said, everyone should understand that Andy is part of the
> platform-driver-x86 maintainer team so please respect his comments as such.
I know Andy very well, we co-worked with PMC driver before, it was a
nice process.
>
>>>
>>>
>>>> res = platform_get_resource(pdev, IORESOURCE_MEM,
>>>> PLAT_RESOURCE_ISP_DATA_INDEX);
>>>> - if (!res) {
>>>> - dev_err(&pdev->dev, "Failed to get res of punit ISP data\n");
>>>> - return -ENXIO;
>>>> + ++punit_res;
>>>> + if (res) {
>>>> + *punit_res = *res;
>>>> + dev_info(&pdev->dev, "punit ISP data res: %pR\n", res);
>>>
>>> Okay, what if you re-arrange this to some helper first
>>>
>>
>> Thanks for the idea, but I don't like a helper here, did you see
>> anything harmful of the current implementation?
>
> In both arguments, we need to identify the WHY.
>
> I imagine Andy is trying to reduce the copy and paste potential for error as
> well as error introduction in future patches. There are... 7 or so cases with
> near identical usage, that's a compelling argument for a refactor such as the
> helper Andy suggests.
>
> Aubrey, you said you don't like it. Why is that? Will it not save enough lines
> of code to be worth it? Are you concerned about revalidating the change?
dev_info with different strings makes the helper useless, or more
complex than desired if we have to write a helper here.
Also, we have necessary resource above, which returns directly if there
is a error. For the coding style consistency in a routine, I really
don't like we call platform_get_resource() directly at first and then
put it into a helper later. The current implementation is
straightforward and clean.
>
> In my opinion, a refactor is a good suggestion, but I would be OK with this
> patch as it is and a refactor to follow. I hesitate to do this when the refactor
> is really critical as it may not happen, but in this case, it doesn't seem
> absolutely necessary.
>
>>
>>> int …_assign_res(*pdev, index, *punit_res)
>>> {
>>> struct resource res;
>>> res = platform_get_resource(pdev, …, index);
>>> if (!res)
>>> return -ERRNO;
>>> *punit_res = *res;
>>> dev_dbg(%pR);
>>> return 0;
>>> }
>>>
>>> In this patch you move to optional by
>>> dev_err -> dev_warn
>>>
>>> and use
>>>
>>> if (ret)
>>> dev_warn( "…skip optional resource…" );
>>>
>>> instead of
>>> if (ret) {
>>> dev_err();
>>> return ret;
>>> }
>>>
>>>> }
>>>> - /* This is index 2 to cover ISP data register */
>>>> - *++punit_res = *res;
>>>> - dev_info(&pdev->dev, "punit ISP data res: %pR\n", res);
>>>>
>>>> + /* This is index 3 to cover ISP interface register, optional */
>>>> res = platform_get_resource(pdev, IORESOURCE_MEM,
>>>> PLAT_RESOURCE_ISP_IFACE_INDEX);
>>>> - if (!res) {
>>>> - dev_err(&pdev->dev, "Failed to get res of punit ISP iface\n");
>>>> - return -ENXIO;
>>>> + ++punit_res;
>>>> + if (res) {
>>>> + *punit_res = *res;
>>>> + dev_info(&pdev->dev, "punit ISP interface res: %pR\n", res);
>>>> }
>>>> - /* This is index 3 to cover ISP interface register */
>>>> - *++punit_res = *res;
>>>> - dev_info(&pdev->dev, "punit ISP interface res: %pR\n", res);
>>>>
>>>> + /* This is index 4 to cover GTD data register, optional */
>>>> res = platform_get_resource(pdev, IORESOURCE_MEM,
>>>> PLAT_RESOURCE_GTD_DATA_INDEX);
>>>> - if (!res) {
>>>> - dev_err(&pdev->dev, "Failed to get res of punit GTD data\n");
>>>> - return -ENXIO;
>>>> + ++punit_res;
>>>> + if (res) {
>>>> + *punit_res = *res;
>>>> + dev_info(&pdev->dev, "punit GTD data res: %pR\n", res);
>>>> }
>>>> - /* This is index 4 to cover GTD data register */
>>>> - *++punit_res = *res;
>>>> - dev_info(&pdev->dev, "punit GTD data res: %pR\n", res);
>>>>
>>>> + /* This is index 5 to cover GTD interface register, optional */
>>>> res = platform_get_resource(pdev, IORESOURCE_MEM,
>>>> PLAT_RESOURCE_GTD_IFACE_INDEX);
>>>> - if (!res) {
>>>> - dev_err(&pdev->dev, "Failed to get res of punit GTD iface\n");
>>>> - return -ENXIO;
>>>> + ++punit_res;
>>>> + if (res) {
>>>> + *punit_res = *res;
>>>> + dev_info(&pdev->dev, "punit GTD interface res: %pR\n", res);
>>>> }
>>>> - /* This is index 5 to cover GTD interface register */
>>>> - *++punit_res = *res;
>>>> - dev_info(&pdev->dev, "punit GTD interface res: %pR\n", res);
>>>>
>>>> res = platform_get_resource(pdev, IORESOURCE_MEM,
>>>> PLAT_RESOURCE_IPC_INDEX);
>>>> diff --git a/drivers/platform/x86/intel_punit_ipc.c b/drivers/platform/x86/intel_punit_ipc.c
>>>> index bd87540..a47a41f 100644
>>>> --- a/drivers/platform/x86/intel_punit_ipc.c
>>>> +++ b/drivers/platform/x86/intel_punit_ipc.c
>>>> @@ -227,6 +227,11 @@ static int intel_punit_get_bars(struct platform_device *pdev)
>>>> struct resource *res;
>>>> void __iomem *addr;
>>>>
>>>> + /*
>>>> + * The following resources are required
>>>> + * - BIOS_IPC BASE_DATA
>>>> + * - BIOS_IPC BASE_IFACE
>>>> + */
>>>> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>> addr = devm_ioremap_resource(&pdev->dev, res);
>>>> if (IS_ERR(addr))
>>>> @@ -239,29 +244,40 @@ static int intel_punit_get_bars(struct platform_device *pdev)
>>>> return PTR_ERR(addr);
>>>> punit_ipcdev->base[BIOS_IPC][BASE_IFACE] = addr;
>>>>
>>>> + /*
>>>> + * The following resources are optional
>>>> + * - ISPDRIVER_IPC BASE_DATA
>>>> + * - ISPDRIVER_IPC BASE_IFACE
>>>> + * - GTDRIVER_IPC BASE_DATA
>>>> + * - GTDRIVER_IPC BASE_IFACE
>>>> + */
>>>> res = platform_get_resource(pdev, IORESOURCE_MEM, 2);
>>>> - addr = devm_ioremap_resource(&pdev->dev, res);
>>>> - if (IS_ERR(addr))
>>>> - return PTR_ERR(addr);
>>>> - punit_ipcdev->base[ISPDRIVER_IPC][BASE_DATA] = addr;
>>>> + if (res) {
>>>> + addr = devm_ioremap_resource(&pdev->dev, res);
>>>> + if (!IS_ERR(addr))
>>>> + punit_ipcdev->base[ISPDRIVER_IPC][BASE_DATA] = addr;
>>>> + }
>>>
>>> And here, what about just replacing return to dev_warn()?
>>
>> I don't think we need to continue the subsequent ops if an error address
>> returns.
>
> Why is that? Will the driver fail to provide any functionality? Or could it be
> the other IFACEs could still be of some use?
>
> This one does need a justification.
>
We discussed this.
- For the necessary resources, if we obtain an error address, we should
return immediately.
- For the optional resources, we keep quiet if we don't get them, that
is, not throwing a warning out.
Thanks,
-Aubrey
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