Re: Loongson 2F IDE/ATA broken with lemote2f_defconfig

[Aaro Koskinen <aaro.koskinen@iki.fi>]

Hi,

On Sun, Jan 06, 2019 at 02:46:07PM +0200, Aaro Koskinen wrote:
> Commit 7ff7a5b1bfff ("MIPS: lemote2f_defconfig: Convert to use libata
> PATA drivers") switched from IDE to libata PATA on Loongson 2F, but
> neither PATA_AMD or PATA_CS5536 work well on this platform compared
> to the AMD74XX IDE driver.
> 
> During the ATA init/probe there is interrupt storm from irq 14, and
> majority of system boots end up with "nobody cared... IRQ disabled".
> So the result is a very slow disk access.
> 
> It seems that the interrupt gets crazy after the port freeze done early
> during the init, and for whatever reason it cannot be cleared.
> 
> With the below workaround I was able to boot the system normally. I
> guess that rather than going back to old IDE driver, we should just try
> to make pata_cs5536 work (and forget PATA AMD on this board)...?

Hmm, even with this hack I get ~500 spurious IRQs during the boot.

Also compared to old IDE, there's 33 vs 100 speed difference:

[    3.324000] ata1: PATA max UDMA/100 cmd 0x1f0 ctl 0x3f6 bmdma 0x4ce0 irq 14
[    3.584000] ata1.00: ATA-8: WDC WD1600BEVS-00VAT0, 11.01A11, max UDMA/133
[    3.588000] ata1.00: 312581808 sectors, multi 16: LBA48
[    3.592000] ata1.00: limited to UDMA/33 due to 40-wire cable

[    4.540000] Probing IDE interface ide0...
[    4.992000] hda: WDC WD1600BEVS-00VAT0, ATA DISK drive
[    5.716000] hda: host max PIO5 wanted PIO255(auto-tune) selected PIO4
[    5.716000] hda: UDMA/100 mode selected

A.

> diff --git a/drivers/ata/pata_cs5536.c b/drivers/ata/pata_cs5536.c
> index dc1255294628..71e485547ee8 100644
> --- a/drivers/ata/pata_cs5536.c
> +++ b/drivers/ata/pata_cs5536.c
> @@ -229,6 +229,16 @@ static void cs5536_set_dmamode(struct ata_port *ap, struct ata_device *adev)
>  	cs5536_write(pdev, ETC, etc);
>  }
>  
> +static void cs5536_noop_freeze(struct ata_port *ap)
> +{
> +	/*
> +	 * Some CS5536 controllers result in a screaming interrupt if ATA_NIEN
> +	 * is manipulated. Leave it alone and just clear pending IRQ.
> +	 */
> +	ap->ops->sff_check_status(ap);
> +	ata_bmdma_irq_clear(ap);
> +}
> +
>  static struct scsi_host_template cs5536_sht = {
>  	ATA_BMDMA_SHT(DRV_NAME),
>  };
> @@ -238,6 +248,7 @@ static struct ata_port_operations cs5536_port_ops = {
>  	.cable_detect		= cs5536_cable_detect,
>  	.set_piomode		= cs5536_set_piomode,
>  	.set_dmamode		= cs5536_set_dmamode,
> +	.freeze			= cs5536_noop_freeze,
>  };
>  
>  /**