[PATCH v3] ata: pata_at91.c bugfix for high master clock

[PATCH v3] ata: pata_at91.c bugfix for high master clock

[Igor Plyatov]

The AT91SAM9 microcontrollers with master clock higher then 105 MHz
and PIO0, have overflow of the NCS_RD_PULSE value in the MSB. This
lead to "NCS_RD_PULSE" pulse longer then "NRD_CYCLE" pulse and driver
does not detect ATA device.

Signed-off-by: Igor Plyatov <plyatov@gmail.com>
---
 drivers/ata/pata_at91.c |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/drivers/ata/pata_at91.c b/drivers/ata/pata_at91.c
index d1aaeb5..3c2bf86 100644
--- a/drivers/ata/pata_at91.c
+++ b/drivers/ata/pata_at91.c
@@ -33,11 +33,12 @@
 
 
 #define DRV_NAME "pata_at91"
-#define DRV_VERSION "0.1"
+#define DRV_VERSION "0.2"
 
 #define CF_IDE_OFFSET	    0x00c00000
 #define CF_ALT_IDE_OFFSET   0x00e00000
 #define CF_IDE_RES_SIZE     0x08
+#define NCS_RD_PULSE_LIMIT  0x3f /* maximal value for pulse bitfields */
 
 struct at91_ide_info {
 	unsigned long mode;
@@ -110,6 +111,11 @@ static void set_smc_timing(struct device *dev,
 	/* (CS0, CS1, DIR, OE) <= (CFCE1, CFCE2, CFRNW, NCSX) timings */
 	ncs_read_setup = 1;
 	ncs_read_pulse = read_cycle - 2;
+	if (ncs_read_pulse > NCS_RD_PULSE_LIMIT) {
+		ncs_read_pulse = NCS_RD_PULSE_LIMIT;
+		dev_warn(dev, "ncs_read_pulse limited to maximal value %lu\n",
+			ncs_read_pulse);
+	}
 
 	/* Write timings same as read timings */
 	write_cycle = read_cycle;
-- 
1.7.1

Re: [PATCH v3] ata: pata_at91.c bugfix for high master clock

[Igor Plyatov]

Hi!

Please abandon this patch and use its new version 4 with subjects:
* "[PATCH v4 1/2] ata: pata_at91.c bugfix for initial_timing
initialisation"
* "[PATCH v4 2/2] ata: pata_at91.c bugfix for high master clock"

Best regards!
--
Igor Plyatov

> The AT91SAM9 microcontrollers with master clock higher then 105 MHz
> and PIO0, have overflow of the NCS_RD_PULSE value in the MSB. This
> lead to "NCS_RD_PULSE" pulse longer then "NRD_CYCLE" pulse and driver
> does not detect ATA device.
> 
> Signed-off-by: Igor Plyatov <plyatov@gmail.com>
> ---
>  drivers/ata/pata_at91.c |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/ata/pata_at91.c b/drivers/ata/pata_at91.c
> index d1aaeb5..3c2bf86 100644
> --- a/drivers/ata/pata_at91.c
> +++ b/drivers/ata/pata_at91.c
> @@ -33,11 +33,12 @@
>  
> 
>  #define DRV_NAME "pata_at91"
> -#define DRV_VERSION "0.1"
> +#define DRV_VERSION "0.2"
>  
>  #define CF_IDE_OFFSET	    0x00c00000
>  #define CF_ALT_IDE_OFFSET   0x00e00000
>  #define CF_IDE_RES_SIZE     0x08
> +#define NCS_RD_PULSE_LIMIT  0x3f /* maximal value for pulse bitfields */
>  
>  struct at91_ide_info {
>  	unsigned long mode;
> @@ -110,6 +111,11 @@ static void set_smc_timing(struct device *dev,
>  	/* (CS0, CS1, DIR, OE) <= (CFCE1, CFCE2, CFRNW, NCSX) timings */
>  	ncs_read_setup = 1;
>  	ncs_read_pulse = read_cycle - 2;
> +	if (ncs_read_pulse > NCS_RD_PULSE_LIMIT) {
> +		ncs_read_pulse = NCS_RD_PULSE_LIMIT;
> +		dev_warn(dev, "ncs_read_pulse limited to maximal value %lu\n",
> +			ncs_read_pulse);
> +	}
>  
>  	/* Write timings same as read timings */
>  	write_cycle = read_cycle;

Re: [PATCH v3] ata: pata_at91.c bugfix for high master clock

[Stanislaw Gruszka]

On Mon, Mar 28, 2011 at 03:59:55PM +0400, Igor Plyatov wrote:
> The AT91SAM9 microcontrollers with master clock higher then 105 MHz
> and PIO0, have overflow of the NCS_RD_PULSE value in the MSB. This
> lead to "NCS_RD_PULSE" pulse longer then "NRD_CYCLE" pulse and driver
> does not detect ATA device.
> 
> Signed-off-by: Igor Plyatov <plyatov@gmail.com>
> ---
>  drivers/ata/pata_at91.c |    8 +++++++-
>  1 files changed, 7 insertions(+), 1 deletions(-)
> 
> diff --git a/drivers/ata/pata_at91.c b/drivers/ata/pata_at91.c
> index d1aaeb5..3c2bf86 100644
> --- a/drivers/ata/pata_at91.c
> +++ b/drivers/ata/pata_at91.c
> @@ -33,11 +33,12 @@
>  
>  
>  #define DRV_NAME "pata_at91"
> -#define DRV_VERSION "0.1"
> +#define DRV_VERSION "0.2"
>  
>  #define CF_IDE_OFFSET	    0x00c00000
>  #define CF_ALT_IDE_OFFSET   0x00e00000
>  #define CF_IDE_RES_SIZE     0x08
> +#define NCS_RD_PULSE_LIMIT  0x3f /* maximal value for pulse bitfields */
>  
>  struct at91_ide_info {
>  	unsigned long mode;
> @@ -110,6 +111,11 @@ static void set_smc_timing(struct device *dev,
>  	/* (CS0, CS1, DIR, OE) <= (CFCE1, CFCE2, CFRNW, NCSX) timings */
>  	ncs_read_setup = 1;
>  	ncs_read_pulse = read_cycle - 2;
> +	if (ncs_read_pulse > NCS_RD_PULSE_LIMIT) {
> +		ncs_read_pulse = NCS_RD_PULSE_LIMIT;

It's ATA specification break, I explained this already here:
http://marc.info/?l=linux-ide&m=129254321006232&w=2
Do we want fix that do not conform specification?

Stanislaw