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RE: [PATCH] hw/ssi: imx_spi: Improve chip select handling
From: |
Cheng, Xuzhou |
Subject: |
RE: [PATCH] hw/ssi: imx_spi: Improve chip select handling |
Date: |
Sat, 18 Sep 2021 03:09:34 +0000 |
> > I got some free time in the past days to investigate this issue. Guenter is
> > right, the Linux imx-spi driver does not work on QEMU.
> >
> > The reason is that the state of m25p80 machine loops in STATE_READING_DATA
> > state after receiving RDSR command, the new command is ignored. Before
> > sending a new command, the CS line should be pulled to high, this make the
> > state of m25p80 back to IDLE.
> >
> > I have same point with Guenter, it's that set CS to 1 when burst is zero.
> > But i don't think it is necessary to set CS to 0 in imx_spi_flush_txfifo().
> > I will send a new patch to fix this issue.
> >
>
> Thanks a lot for looking into this. If you have a better solution than mine,
> by all means, please go for it. As I mentioned in my patch, I didn't really
> like it, but I was unable to find a better solution.
I am doing some experiment to verify that the new patch is reasonable, so the
new patch will be delayed few days.
>
> > BTW, the Linux driver uses DMA mode when transfer length is greater than
> > the FIFO size, But QEMU imx-spi model doesn't support DMA now.
>
> Does it have practical impact ? Obviously my tests were somewhat limited (I
> was happy to get Linux booting from flash), but I don't recall seeing a
> problem.
There seem have no practical impact. :)
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, (continued)
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Guenter Roeck, 2021/09/04
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Bin Meng, 2021/09/04
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Philippe Mathieu-Daudé, 2021/09/04
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Guenter Roeck, 2021/09/04
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Bin Meng, 2021/09/08
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Bin Meng, 2021/09/08
- RE: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Cheng, Xuzhou, 2021/09/08
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Guenter Roeck, 2021/09/08
- RE: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Cheng, Xuzhou, 2021/09/16
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Guenter Roeck, 2021/09/16
- RE: [PATCH] hw/ssi: imx_spi: Improve chip select handling,
Cheng, Xuzhou <=
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Guenter Roeck, 2021/09/18
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Bin Meng, 2021/09/25
- Re: [PATCH] hw/ssi: imx_spi: Improve chip select handling, Guenter Roeck, 2021/09/04