Unable to read sector for atapi device

[dansmahajan]

Hi, I am writing a atapi driver to implement iso9660 filesystem but after reading a sector i am unable to read the same sector or any other sector

Code: Select all

void atapi_read_pio(u32int bus, u32int drive, u32int lba, u32int num_lba,u8int *buffer)
{	
	u8int read_pkt[12] = {0,0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0 }; 

	read_pkt[2] = (lba >> 0x18) & 0xFF;   /* most sig. byte of LBA */
    read_pkt[3] = (lba >> 0x10) & 0xFF;
    read_pkt[4] = (lba >> 0x08) & 0xFF;
    read_pkt[5] = (lba >> 0x00) & 0xFF;   /* least sig. byte of LBA */
	
	if(num_lba > 0xFFFF)
	{
		//read12 command
		read_pkt[0] = ATAPI_READ12_CMD;
		read_pkt[6] = (num_lba >> 0x18) & 0xFF;		//msb transfer len
		read_pkt[7] = (num_lba >> 0x10) & 0xFF;
		read_pkt[8] = (num_lba >> 0x08) & 0xFF;
		read_pkt[9] = (num_lba >> 0x00) & 0xFF;		//lsb transfer len
	}
	else
	{
		//read10 command
		read_pkt[0] = ATAPI_READ10_CMD;
		read_pkt[7] = (num_lba >> 0x08) & 0xFF;		//msb transfer len
		read_pkt[8] = (num_lba >> 0x00) & 0xFF;	//lsb transfer len
	}
	
	//atapi pkt req 6 words to be pushed not 12 bytes
	u16int read_pkt_w[6];
	int i,j;
	for(i=0,j=0;i<6;i++,j+=2)
	read_pkt_w[i] = read_pkt[j+1]<<8 | read_pkt[j];
	
	//Selecting up device to be read from
	outportb(ATA_DRIVE_SELECT_PORT(bus),drive);
	outportb(ATA_FEATURES_PORT(bus),0);
		
	outportb (ATA_LBA_MID_PORT(bus), ATAPI_SECTOR_SIZE & 0xFF);
    outportb (ATA_LBA_HI_PORT(bus), ATAPI_SECTOR_SIZE >> 8);
	
	
	//ATATPI PKT cmd
	outportb(ATA_COMMAND_PORT(bus),ATAPI_PKT_CMD);
	
	//waiting for dev to get ready
	while((inportb(ATA_STATUS_PORT(bus)) & ATA_STATUS_REG_BSY)
	&& !(inportb(ATA_STATUS_PORT(bus)) & ATA_STATUS_REG_DRQ) );
	
	//pushing the packet to the data port
	for(i=0;i<6;i++)
		outportw(ATA_DATA_PORT(bus),read_pkt_w[i]);
	
	//IRQ response wait***not implemented
	while((inportb(ATA_STATUS_PORT(bus)) & ATA_STATUS_REG_BSY)
	&& !(inportb(ATA_STATUS_PORT(bus)) & ATA_STATUS_REG_DRQ) );
	if(( inportb(ATA_STATUS_PORT(bus)) & ATA_STATUS_REG_ERR))kprintf("WTF JJJJJJJJ");
	//timer_wait(12);
	//a=true;
	//wait_for_interrupt();
	
	//Actual size that is to transferred
	u32int size =
      (((u32int) inportb (ATA_LBA_HI_PORT (bus))) << 8) | (u32int) (inportb (ATA_LBA_MID_PORT (bus)));
    
    kprintf("\nActual Size to be transferred 0x%x",size);
    
    u16int words = size/2;
    //transferring data
    u16int temp;
    for(i=0,j=0;i<words;i++)
    {
		temp = inportw (ATA_DATA_PORT (bus));
		buffer[j++] = temp & 0xFF;
		buffer[j++] = (temp>>8) & 0xFF;
	}
}

above is the code to read a sector from atapi device

Code: Select all

iso9660_vol_desc_primary *pri;
	
	iso9660_vol_desc *vol_desc = (iso9660_vol_desc *)kmalloc(sizeof(iso9660_vol_desc));
	
	atapi_read_pio(bus, drive, ISO9660_VOL_DESC_START_SECTOR+0, 1,(u8int *)vol_desc);

	pri = (iso9660_vol_desc_primary *)vol_desc;
	
	iso9660_dir_record root_dir = (iso9660_dir_record)&pri->root_dir_entry;
	
	iso9660_dir_table root = (iso9660_dir_table)kmalloc(ISO9660_LOGICAL_SECTOR_SIZE);	//*******
	
	atapi_read_pio(bus, drive, iso9660_dir_record_get_lba(root_dir),1,root);
	

for the first time i can read the sector properly ie i am able to see all the directories and files in the root dir but if i try to read the root dir again or some sub dir only 0xc bytes are transferred

so what am i missing here ??

PS i know IRQ should be used for transfer but interrupt is fired too quickly before the scheduler can queue the process to the driver queue

[Combuster]

PS i know IRQ should be used for transfer but interrupt is fired too quickly before the scheduler can queue the process to the driver queue

Which means you have bigger issues.

[dansmahajan]

yeah...but right now i am not concentrating on that
If the problem was related to IRQ then i wouldn't have read the sector in the first place

[dansmahajan]

i guess i found a temporary solution...since after reading a sector i was not able to read that sector again so i tried to reset the device and then it worked-was able to read the sector again..

so every time reading a sector i have to reset the device ??? or there is a better way to do it ??