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Message-ID: <2f8a3abd-c837-47a6-93a0-b3d8927620af@samsung.com>
Date: Fri, 17 Jan 2025 16:58:43 +0100
From: Marek Szyprowski <m.szyprowski@...sung.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: Mark Brown <broonie@...nel.org>, linux-kernel@...r.kernel.org, Greg
Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki"
<rafael@...nel.org>, Danilo Krummrich <dakr@...nel.org>, Dmitry Baryshkov
<dmitry.baryshkov@...aro.org>, DRI mailing list
<dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH v3 1/1] regmap: Synchronize cache for the page selector
On 17.01.2025 15:09, Andy Shevchenko wrote:
> On Fri, Jan 17, 2025 at 02:57:52PM +0100, Marek Szyprowski wrote:
>> On 16.01.2025 13:42, Andy Shevchenko wrote:
>>> If the selector register is represented in each page, its value
>>> in accordance to the debugfs is stale because it gets synchronized
>>> only after the real page switch happens. Synchronize cache for
>>> the page selector.
>>>
>>> Before (offset followed by hexdump, the first byte is selector):
>>>
>>> // Real registers
>>> 18: 05 ff 00 00 ff 0f 00 00 f0 00 00 00
>>> ...
>>> // Virtual (per port)
>>> 40: 05 ff 00 00 e0 e0 00 00 00 00 00 1f
>>> 50: 00 ff 00 00 e0 e0 00 00 00 00 00 1f
>>> 60: 01 ff 00 00 ff ff 00 00 00 00 00 00
>>> 70: 02 ff 00 00 cf f3 00 00 00 00 00 0c
>>> 80: 03 ff 00 00 00 00 00 00 00 00 00 ff
>>> 90: 04 ff 00 00 ff 0f 00 00 f0 00 00 00
>>>
>>> After:
>>>
>>> // Real registers
>>> 18: 05 ff 00 00 ff 0f 00 00 f0 00 00 00
>>> ...
>>> // Virtual (per port)
>>> 40: 00 ff 00 00 e0 e0 00 00 00 00 00 1f
>>> 50: 01 ff 00 00 e0 e0 00 00 00 00 00 1f
>>> 60: 02 ff 00 00 ff ff 00 00 00 00 00 00
>>> 70: 03 ff 00 00 cf f3 00 00 00 00 00 0c
>>> 80: 04 ff 00 00 00 00 00 00 00 00 00 ff
>>> 90: 05 ff 00 00 ff 0f 00 00 f0 00 00 00
>>>
>>> Fixes: 6863ca622759 ("regmap: Add support for register indirect addressing.")
>>> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
>> This patch landed in linux-next some time ago as commit 1fd60ed1700c
>> ("regmap: Synchronize cache for the page selector"). Today I've noticed
>> that it causes a regression for Lontium LT9611UXC HDMI bridge driver.
> Is there any datasheet link to the HW in question?
>
> (FWIW, I have tested this with the CY8C9540 GPIO I²C expander on Intel Galileo
> Gen 1 board.)
I'm not aware of it, but I'm not related to lt9611uxc driver development
at all...
>> With today's linux-next I got the following messages on QCom RB5 board:
>>
>> # dmesg | grep lt9611uxc
>> [ 13.737346] lt9611uxc 5-002b: LT9611 revision: 0x00.00.00
>> [ 13.804190] lt9611uxc 5-002b: LT9611 version: 0x00
>> [ 13.870564] lt9611uxc 5-002b: FW version 0, enforcing firmware update
>> [ 13.877437] lt9611uxc 5-002b: Direct firmware load for
>> lt9611uxc_fw.bin failed with error -2
>> [ 13.887517] lt9611uxc 5-002b: probe with driver lt9611uxc failed with
>> error -2
>>
>> after reverting the $subject patch, the driver probes fine on that board.
>>
>> I'm not sure if this is really a bug caused by this change or simply the
>> driver already was aligned to old regmap behavior. Dmitry, could you
>> check the regamp usage and review the changes introduced by this patch?
>> Let me know if there is anything to check on the real hardware to help
>> resolving this issue.
> Yes, see below. And thank you for your report!
>
> ...
>
>>> + /*
>>> + * If selector register has been just updated, update the respective
>>> + * virtual copy as well.
>>> + */
>>> + if (page_chg &&
>>> + in_range(range->selector_reg, range->window_start, range->window_len))
>>> + _regmap_update_bits(map, sel_register, mask, val, NULL, false);
> Can you add a test printk() here to show
>
> page_chg
> range->selector_reg, range->window_start, range->window_len
> sel_register, mask, val
>
> ?
>
> And would commenting these three lines make it work again?
I've added the following debug message before that check:
printk("page_chg %d range->selector_reg %x range->window_start %x
range->window_len %x sel_register %x mask %x val %x\n", page_chg,
range->selector_reg, range->window_start, range->window_len,
sel_register, mask, val);
Here is the result:
root@...get:~# modprobe lontium_lt9611uxc
[ 29.892962] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 80ff mask ff val 80
[ 29.907419] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 81ff mask ff val 81
[ 29.926712] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 81ff mask ff val 81
[ 29.958301] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 81ff mask ff val 81
[ 29.979951] lt9611uxc 5-002b: LT9611 revision: 0x00.00.00
[ 29.987002] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 80ff mask ff val 80
[ 30.052370] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 80ff mask ff val 80
[ 30.066808] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register b0ff mask ff val b0
[ 30.079859] lt9611uxc 5-002b: LT9611 version: 0x00
[ 30.085990] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 80ff mask ff val 80
[ 30.151735] lt9611uxc 5-002b: FW version 0, enforcing firmware update
[ 30.158830] lt9611uxc 5-002b: Direct firmware load for
lt9611uxc_fw.bin failed with error -2
[ 30.168653] lt9611uxc 5-002b: probe with driver lt9611uxc failed with
error -2
after disabling the above mentioned 3 lines:
root@...get:~# modprobe lontium_lt9611uxc
[ 44.584893] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 80ff mask ff val 80
[ 44.597589] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 81ff mask ff val 81
[ 44.609936] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 81ff mask ff val 81
[ 44.622277] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 81ff mask ff val 81
[ 44.634579] lt9611uxc 5-002b: LT9611 revision: 0x17.04.93
[ 44.641444] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 80ff mask ff val 80
[ 44.710694] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 80ff mask ff val 80
[ 44.724579] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register b0ff mask ff val b0
[ 44.736853] lt9611uxc 5-002b: LT9611 version: 0x40
[ 44.743253] page_chg 1 range->selector_reg ff range->window_start 0
range->window_len 100 sel_register 80ff mask ff val 80
[ 44.816433] msm_dpu ae01000.display-controller: bound ae94000.dsi
(ops dsi_ops [msm])
[ 44.843944] msm_dpu ae01000.display-controller: bound
ae90000.displayport-controller (ops msm_dp_display_comp_ops [msm])
[ 44.862886] adreno 3d00000.gpu: supply vdd not found, using dummy
regulator
[ 44.870974] adreno 3d00000.gpu: supply vddcx not found, using dummy
regulator
[ 44.897116] platform 3d6a000.gmu: Adding to iommu group 27
[ 44.938871] msm_dpu ae01000.display-controller: bound 3d00000.gpu
(ops a3xx_ops [msm])
[ 44.952435] [drm:dpu_kms_hw_init:1156] dpu hardware revision:0x60000000
[ 44.976496] [drm] Initialized msm 1.12.0 for
ae01000.display-controller on minor 0
...
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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