Hi Carlos, On 20.12.24 10:23, Carlos Song wrote: >>> Hi, the ret is from i2c_imx_dma_request() and look like that ret has >>> been converted by PTR_ERR, So the ret error has been human readable >> version? >> >> I am not sure I understand the question. ERR_PTR() makes an error pointer >> and %pe formats that pointer as error message. So you don't need to change >> any function return types unless needed, just at the end print it with %pe >> instead of %d (and after error pointer conversion if needed). > > Sorry, I don't know if I understand it incorrectly. > I review other driver code, most choose to return error value but not an error pointer. > Shouldn't error value be more readable than error pointers? > When we see -110 we know TIMEOUT and we see -12 we know NO MEM. I know -110, but -12 I need to look up :) Both are cryptic to end users, which is why %pe was added on top of the existing %p: If CONFIG_SYMBOLIC_ERRNAME is enabled %pe expands to an error string, e.g. "ENOMEM" or "ETIMEDOUT". If it's disabled, you get the same error number that was printed raw before. Cheers, Ahmad > > i2c_imx_dma_request is using PTR_ERR to convert pointer to error value[1]. > I don't know why need to use ERR_PTR to reconvert the value to pointer: > > dev_err(&pdev->dev, "Failed to setup DMA (%pe), only use PIO mode\n", ERR_PTR(ret)); > > Is there some strong reason? > > [1] https://lore.kernel.org/imx/AM0PR0402MB3937419BBB58B75FB8F8DE2DE8072@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx/ >> >> -- >> Pengutronix e.K. | >> | >> Steuerwalder Str. 21 | >> http://www.pen/ >> gutronix.de%2F&data=05%7C02%7Ccarlos.song%40nxp.com%7C594497db1b5 >> 44e479a8f08dd20d1e88e%7C686ea1d3bc2b4c6fa92cd99c5c301635%7C0%7C0 >> %7C638702808104903131%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGki >> OnRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ >> %3D%3D%7C0%7C%7C%7C&sdata=EnhsIFlBooqjB%2FSRWF7uAqRHE3yN6rbdD >> 1yQueTrRus%3D&reserved=0 | >> 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 >> | >> Amtsgericht Hildesheim, HRA 2686 | Fax: >> +49-5121-206917-5555 | -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
