Messages in this thread | | | Subject | Re: [PATCH] spi: Add PXA2xx SSP SPI Driver | From | Stephen Street <> | Date | Tue, 07 Feb 2006 13:17:34 -0800 |
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On Tue, 2006-02-07 at 11:50 +0000, David Vrabel wrote: > PXA27x has a clock speed of 13000000 Hz. > Yea... And this affects the divisor calculation depending on type of CPU and when the CPU is a PXA260 or PXA25x which SSP port. And worse, the SSP controller (as opposed to the NSSP/ASSP) on the PXA25x and PXA260 use a different divisor calculation:
Serial Bit Rate = SSP Port Clock / 2 / (SCR + 1)
The pxa_regs.h file is misleading and potentially inaccurate in this respect.
> Consider spi->max_speed_hz == CLOCK_SPEED_HZ which gives a divisor of 3 > (when it should be 1). > > You need SSCR0_SerClkDiv(CLOCK_SPEED_HZ / (spi->max_speed_hz + 1) + 1) > for the correct divisor and for proper rounding. Yes, but see qualification above. I will fix this as you suggest, with some modifications. FYI The CPU differences also exposed a similar problem with the DMA setup. Thanks!
> > > + /* Attach to IRQ */ > > + irq = platform_get_irq(pdev, 0); > > + if (irq == 0) { > > + dev_err(&pdev->dev, "irq resource not defined\n"); > > + status = -ENODEV; > > + goto out_error_master_alloc; > > + } > > Greg K-H has a patch pending that makes platform_get_irq() return -ENXIO > instead of 0 on error. This is required for SSP3 on the PXA27x which > uses IRQ 0. > > > + /* Release IRQ */ > > + irq = platform_get_irq(pdev, 0); > > + if (irq != 0) > > + free_irq(irq, drv_data); > > Similarly.
Will do.
I will re-post the patch again to today. Thanks for the help.
-Stephen
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