[PATCH v8 2/5] i2c: mediatek: Dump i2c/dma register when a timeout occurs

[Boris Lysov]

On Sun, 10 Oct 2021 15:05:13 +0800
Kewei Xu <kewei.xu at mediatek.com> wrote:

> When a timeout error occurs in i2c transter, it is usually related
> to the i2c/dma IP hardware configuration. Therefore, the purpose of
> this patch is to dump the key register values of i2c/dma when a
> timeout occurs in i2c for debugging.
> 
> Signed-off-by: Kewei Xu <kewei.xu at mediatek.com>
> Reviewed-by: Qii Wang <qii.wang at mediatek.com>

I would like to test this patchset on one of supported platforms, an
mt6577-powered device. This driver requires a DMA base...
> 	i2c->pdmabase = devm_ioremap_resource(&pdev->dev, res);
>	if (IS_ERR(i2c->pdmabase))
>		return PTR_ERR(i2c->pdmabase);
... however I am not sure what address should I specify in the .dts file. While
other i2c busses supported by this driver such as mt6589 [1][2] and mt6797 [3]
have designated DMA for I2C, mt6577 seems to lack dedicated DMA engine for I2C
[4][5].

Do I need to specify the Generic DMA base address [4] instead?

Worth mentioning I brought up this issue in the past [5][6].

[1] ALPS.KK1.MP5.V1.3_EASTAEON89_WET_KK source code (downstream)
[2] MT6589 HSPA+ Smartphone Application Processor Datasheet v1.0, page 869
[3] MT6797 LTE-A Smartphone Application Processor Register Table (Part 1) v1.1,
page 1796
[4] MT6577 HSPA Smartphone Application Processor Datasheet v0.94, page 547
[5] ALPS.JB.MP.V1.19_MBK77_TB_JB source code (downstream)
[6] https://marc.info/?l=devicetree&m=159949247901831&w=2
[7] https://marc.info/?l=linux-i2c&m=159939730714187&w=2